Microsoft KB Archive/936211

= How to troubleshoot network connectivity problems in Internet Explorer =

Article ID: 936211

Article Last Modified on 4/25/2007

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APPLIES TO


 * Windows Internet Explorer 7 in Windows Vista

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INTRODUCTION
This article describes how to troubleshoot network connectivity problems in Internet Explorer.



Step 1. Use the Network Diagnostic tool
The Network Diagnostics tool that is part of Windows Vista is designed to test the network connection for errors. The Network Diagnostics tool can also be used to determine whether network-related programs are working correctly. To use this tool to troubleshoot network connectivity problems, follow these steps:
 * 1) Open Internet Explorer, and try to access the Web page that causes network connectivity problems.
 * 2) On the page that displays an Internet Explorer error message, click the Diagnose Connection Problems link.

The Network Diagnostics tool will run. When the tool has finished running, it will report one of the following results:
 * It was unable to find a problem.
 * It has detected a problem. Additionally, the tool will provide guidance on the next steps to take to troubleshoot the problem.

If you cannot resolve the problem by using the Network Diagnostics tool, you must manually troubleshoot the problem. To do this, go to the &quot;Manually troubleshoot the problem&quot; section.

Method 1: Test other known good sites
Start Internet Explorer, and then enter one of the following addresses in the Address bar at the top of the browser window:

http://www.microsoft.com

http://www.msn.com

http://www.hotmail.com

If you do not experience network connectivity problems when you type one of these addresses in the Address bar, we recommend that you contact the owner of the Web site where you see the problem. The site may be temporarily offline or experiencing other issues of its own.

However, if you continue to experience network connectivity problems when you type one of these addresses in the Address bar, there may be a conflict with other software that is installed on the system. In this case, go to the method 2.

Method 2: Verify the network connection
Make sure that the cables that connect the computer to the Internet or your home network are secured firmly. Additionally, make sure that the network devices that your computer uses are turned on and working correctly. Then, follow these steps to verify network connectivity, as appropriate for your situation.

Step 1: Verify external DSL modem, cable modem or dial-up modem connectivity
If you use an external modem, check the following:  Verify that the cable that connects the modem to the wall is connected securely. The cable will most likely connect to either a telephone jack or to a cable outlet. Verify that the cable that connects the computer to the modem is attached securely at both ends and that the connector on each end of the cable has clicked into position if it is a network cable. A network cable will resemble a telephone cable, although it may be thicker, and the connector on each end will be larger. If the cable that connects the external modem to the computer is a USB cable, you must perform some additional checks. A USB cable will have different connectors on each end of the cable. One end will be flat and rectangular, and the other end will have a square connector with angles on two of the corners. To verify a USB connection, try the following:  If the modem is attached to the computer by using a USB hub, try to bypass the USB hub. You can bypass the USB hub by plugging the cable from the device directly into one of the USB ports on the computer. If the modem is plugged into one of the ports on the front of your desktop computer, try plugging the USB cable into one of the ports on the back of the computer instead. Some computers do not provide sufficient power to the front USB ports. This may create problems with the connection to the modem. 

Step 2: Verify the internal modem device connections
If the modem that is used to connect to the Internet is inside the computer, there should be only one cable coming out of the modem device. Verify that the cable that connects the modem to the wall outlet is connected securely at each end. The cable will most likely connect to either a telephone jack or a cable outlet.

Step 3: Verify the home network connectivity
If the computer connects to the Internet through a home network, we recommend that you check the items in the following list, as appropriate for your situation. <ul> Wireless connection

If the computer uses a wireless connection to the home network, we recommend that you read the following articles on the &quot;Windows Vista Help and How-to Web&quot; site: <ul> To troubleshoot problems that are related to detecting wireless networks, visit the following Microsoft Web site:

http://windowshelp.microsoft.com/Windows/en-US/Help/7805207d-b0b9-4159-b36f-ab81a1f376c21033.mspx

</li> To troubleshoot problems that are related to low wireless signal quality, visit the following Microsoft Web site:

http://windowshelp.microsoft.com/Windows/en-US/Help/fbb50492-3623-450d-8fd5-92cc74fab0ae1033.mspx

</li></ul> </li> Wired connection

If the computer uses a wired connection (This connection is also known as an Ethernet connection.), we recommend that you read the &quot;I can’t connect to my home network” section in the following article that is titled “Troubleshoot network and Internet connection problems”:

http://windowshelp.microsoft.com/Windows/en-US/Help/33307acf-0698-41ba-b014-ea0a2eb8d0a81033.mspx

If you want additional guidance about specific network configurations, hardware configurations, or network configurations, we recommend that you contact the vendor of the network hardware that you are using.

Note You may have to contact your Internet service provider (ISP) to verify connectivity.</li></ul>

Method 3: Other connectivity issues or network-related issues
One potential cause of network connectivity problems is that the network or the Internet connection that you are using to go online is experiencing a problem. You can test for this by using the following troubleshooting steps:

Step 1. Restart the modem or the router
It is sometimes possible that the IP settings or network configuration that you receive from the Internet service provider are incorrect or must be updated. Sometimes, the connection between the modem and the ISP may be experiencing problems. To update the settings on the modem or the router, you must restart the device. Restarting the device will also create a fresh connection to the Internet service provider. Use one of the following methods to restart the modem, depending on the type of modem that you have.

External modem

To restart an external modem, follow these steps:
 * 1) Disconnect the cable that connects your computer or router to the modem. This may be either a USB cable or a network cable.
 * 2) Turn off the modem. If the modem does not have a power switch, disconnect the power cord from the back of the modem, or unplug it from the wall.
 * 3) After waiting for several minutes, turn on the modem, reconnect the cable from the computer or the router to the modem, and then restart the computer.
 * 4) Test your connection again to see whether you can access the Internet.

If you still experience network connectivity problems, go to step 2.

Internal modem

To restart an internal modem, you must restart the computer. If you still experience network connectivity problems after you restart the computer, go to step 2.

Step 2. Verify the firewall or the router settings
If you connect to the Internet by using a router, there may be a problem with the configuration settings, and they must be updated. To determine whether a network connectivity problem is being caused by a mis-configuration or by a problem with the router, you can bypass the router and connect your computer directly to the modem.

Caution Connecting your computer directly to the Internet may leave it vulnerable to attacks. To protect the computer against attacks, make sure that a firewall is installed and that the firewall is enabled on your computer. To find out about the Windows Firewall that is included in Windows Vista, see the &quot;Windows Firewall&quot; section.

Windows Firewall

Windows Vista includes a firewall called the Windows Firewall. By default, the Windows Firewall is enabled. However, you must still verify that the Windows Firewall is enabled before you connect the computer to the Internet. To verify that the Windows Firewall is enabled, follow these steps:  Click Start, and then click Control Panel.</li> In the search box at the upper-right corner of Control Panel, type security .</li> In the search results that appear, click the icon or the link for Security Center. In the window that is displayed, you will see four bars that are titled Firewall, Automatic updating, Malware protection, and Other security settings.</li> Click the right arrow button on the Firewall bar to expand the bar. The expanded bar will display one of the following three options:  If the Firewall bar is green, it means that the firewall is enabled.</li> If the Firewall bar is red, you may see a message that the Windows Firewall is turned off. To turn on the Windows Firewall and to cause the Firewall bar in security center to turn green, click Turn on now.</li> If the Firewall bar is red, and the message describes a problem with a third-party firewall program, we recommend that you disconnect the computer from the network, and then contact the vendor of that firewall program for more information about how to turn on the third-party firewall program.</li></ol> </li></ol>

For more information about the Windows Firewall in Windows Vista, visit the following &quot;Windows Help and How-to&quot; Web sites: <ul> To read the article, &quot;Firewall: frequently asked questions,&quot; visit the following Microsoft Web site:

http://windowshelp.microsoft.com/Windows/en-US/Help/33307acf-0698-41ba-b014-ea0a2eb8d0a81033.mspx

</li> To read the article, &quot;What is a firewall?,&quot; visit the following Microsoft Web site:

http://windowshelp.microsoft.com/Windows/en-US/Help/4673a386-2e73-4b7a-a333-6f826a3d44b41033.mspx

</li> To find out more about Windows Firewall, read the article, &quot;Windows Firewall: recommended links,&quot; at the following Microsoft Web site:

http://windowshelp.microsoft.com/Windows/en-US/Help/05eee553-6a90-456a-b9e5-fcb4233905431033.mspx

</li> <li>For more information about the relationship between Windows Firewall and Windows Security Center in Windows Vista, click the following article number to view the article in the Microsoft Knowledge Base:

929462 Description of the relationship between Windows Firewall and Windows Security Center in Windows Vista

</li></ul>

After you connect the computer directly to the modem, test Internet Explorer. If you are now able to access the Web sites that you were unable to access before, contact the router's manufacturer for help in configuring the device. If you are still unable to access any Web sites, go to step 3.

Step 3. Verify device compatibility
For a modem or a network adapter to work correctly in Windows Vista, it must be compatible with Windows Vista. Additionally, it must have device drivers that can be used by Windows Vista to communicate with the device. To find out whether the modem or the network adapter that you are using is compatible with Windows Vista, you must first determine what adapter model you have in the computer. To do this, follow these steps: <ol> <li>Click Start, type device manager in the Start Search box, and then press ENTER.</li> <li>Click the entry for Device Manager that appears in the search results.</li> <li>Expand the entry for the type of device that you are looking for. For example, expand Network adapters.

Note The specific type of device that you must look for will be determined by the way that you connect this computer to the Internet. For example, if you connect to the Internet by using a wireless network connection, you must look for information about a wireless network adapter and you must expand Network adapters.</li> <li>Note the entries that appear under Network adapters.</li> <li>On another computer, start Internet Explorer.</li> <li>Type the following address, and then press ENTER:

http://whql.microsoft.com/hcl/

</li> <li>Search for the network adapter that you noted in step 4. Information that is contained on this Web site will tell you if the network adapter is compatible with Windows Vista.</li></ol>

If you cannot determine the type of modem or of network adapter that you have in your computer, or if that device shows that it is experiencing a problem, we recommend that you contact the OEM or the hardware vendor from whom you obtained this adapter. For information about how to contact the OEM or the hardware vendor from whom you obtained this adapter, click the appropriate article number in the following list to view the article in the Microsoft Knowledge Base:

65416 Hardware and software vendor contact information, A-K

60781 Hardware and software vendor contact information, L-P

60782 Hardware and software vendor contact information, Q-Z

If the device that you are looking for is either an internal DSL modem or an internal cable modem, we recommend that you contact the Internet service provider that gave you the modem. Some potential problems that you might see include the following:
 * The modem or the network adapter is missing from Device Manager.
 * The modem or the network adapter is listed as an Unknown Device or with a generic name such as Ethernet Adapter or PCI Simple Communications Controller.
 * The modem or the network adapter is marked with either a red X or a yellow exclamation point.

If you still experience network connectivity problems after you verify that the modem or the network adapter is compatible with Windows Vista and that the latest drivers for the device are installed, go to step 4.

Step 4. Create a System Restore point before you reset the Winsock protocol
Important Before you follow the steps that are described in the &quot;Reset the Winsock protocol&quot; section, we recommend that you use the System Restore tool in Windows Vista to create a restore point on the computer. This will let you roll back the computer to the point in time before any changes were made in case these changes create new problems.

Create a System Restore point

To create a System Restore point by using System Restore, follow these steps: <ol> <li>Click Start, right-click Computer, and then click Properties.</li> <li>In the task pane, click the System protection link. If you are prompted for an administrator password or for a confirmation, type the password, or click Continue.</li> <li>Click Create on the lower-right corner of the System Properties dialog box.</li> <li>In the System Protection dialog box, type a suitable name in the box. For example, type Computer before network changes, and then click Create.</li> <li>As soon as the restore point is successfully created, the following notification is displayed:

The restore point was created successfully.

</li> <li>Click OK two times.</li></ol>

Reset the Winsock protocol

Another possible cause of network connectivity problems is the mis-configuration or the corruption of the Winsock protocol on the computer. This protocol is used by Windows to communicate with other computers and to access resources on the Internet, such as e-mail and Web sites. If there is a problem with Winsock, Windows Vista will no longer be able to access the Internet.

Caution Programs that access or that monitor the Internet, such as antivirus programs, firewall programs, and proxy clients, may be adversely affected when you reset the configuration of the Winsock protocol. If you have a program that no longer functions correctly after you follow these steps, you may have to uninstall and then reinstall the program to restore its functionality, or you may have to repair the program by using the application’s Setup program.

After the restore point has been successfully created, reset the configuration of the Winsock protocol back to its default settings. To do this, follow these steps: <ol> <li>Click Start, and in Start Search, type cmd.</li> <li>Right-click the cmd entry that appears in the search results, and then click Run as administrator. If you are prompted for an administrator password or for a confirmation, type the password, or click Continue.</li> <li>At the command prompt, type the following, and then press ENTER: 

netsh winsock reset

Then, you should see the following message:

Successfully reset the Winsock Catalog. You must restart the computer in order to complete the reset.

</li> <li>Restart the computer.</li></ol>

Note If you receive an “Access Denied” error message instead of the message that is mentioned in step 3, the command prompt was not correctly elevated. In this case, close the Command Prompt window, and repeat steps 1 through 3. Make sure that you correctly implement step 2.

Test Internet Explorer again to see whether network connectivity problems still occur. If you still experience network connectivity problems, go to step 5.

Step 5. Verify the contents of the Hosts file
A Hosts file is used by TCP/IP to provide a method to associate a particular Internet address together with an IP address. Whereas this file has many legitimate uses, some malicious software, such as malware and spyware, can use this file for dubious purposes. The intent of the entries that are included in the Hosts file by malicious software is to prevent you from accessing certain Web sites. For example, you may be prevented from accessing a Web site where you can update your antivirus signatures or where you can access updates. This may leave the computer in a compromised state. Additionally, you cannot access any of the tools that you could use to fix it.

Note In some cases, legitimate entries may be added by system administrators, or you may have added those entries yourself. If you rename a Hosts file, the associations in that file will no longer work. For more information, contact the system administrator or the network administrator.

To determine whether the network connectivity problems that you experience are caused by entries in the Hosts file, you must find and then rename this file so that the entries it contains will no longer be used. To do this, follow these steps: <ol> <li>Click Start, type drivers in the Start Search box, and then press ENTER.</li> <li>Click the entry for drivers that is displayed in the search results. The icon next to drivers will be a folder.</li> <li>A window appears that will display Windows > system32 > drivers in the address bar at the top. Double-click the etc folder.</li> <li>Locate and right-click the hosts file, and then click Rename.</li> <li>Type oldhosts, and then press ENTER. If you receive the following error message click Continue:

You need to confirm this operation.

If you are prompted for an administrator password or for a confirmation, type the password, or click Continue.</li> <li>Restart the computer to make sure that the change takes effect.</li> <li>Test Internet Explorer.</li></ol>

Additional query words: ie

Keywords: kbexpertiseinter kbnetworkcard kbbrowse kbmodem kbnetworkconnectivity kbnetwork_ispspecific kbnetwork_routerissues kbnetwork_checkcables kbadapter kbhowto KB936211

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