Microsoft KB Archive/275042

Knowledge Base

Modem Powers Off When It Is Not in Use

Article ID: 275042

Article Last Modified on 2/20/2007

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APPLIES TO

• Microsoft Windows 2000 Server
• Microsoft Windows 2000 Advanced Server
• Microsoft Windows 2000 Professional Edition

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This article was previously published under Q275042

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

If you have a secure PC Card modem or a similar device that requires you to type a password before it is enabled and you connect to the modem when you start your computer (for example, by using HyperTerminal), when you disconnect from the modem, the modem is automatically powered off by Windows. When this occurs, Windows does not retain your password and you must retype it to enable the modem again.

CAUSE

This problem occurs because power management features automatically power off devices when they are not in use to conserve power.

RESOLUTION

To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

260910 How to Obtain the Latest Windows 2000 Service Pack

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

The English-language version of this fix should have the following file attributes or later:

 Date       Time       Version          Size     File name
-------------------------------------------------------------
 1/23/2001  04:29p     5.0.2195.3177    60,688   Serial.sys
                

After you apply this hotfix, you must add a new value to the registry, and then restart your computer:

1. Click Start, click Run, type regedt32 in the Open box, and then press ENTER.
2. Locate the appropriate device parameters key in the registry, under the HKEY_LOCAL_MACHINE\System\CurrentControlSet\Enum registry key. You can locate the appropriate key manually only.
   
   NOTE: The actual location depends on both the type of device and the actual device.

   HKEY_LOCAL_MACHINE
   \SYSTEM
    \CurrentControlSet
     \Enum
      \<device type>            (for example, "PCMCIA" or "ACPI")
       \<device identifier>     (for example, "Secure CreditCard Modem" or "PNP<I>xxxx</I>")
        \<device id number>     (for example, "1" or another device id string)
         \Device Parameters
                           

3. On the Edit menu, click Add Value, and then add the following registry value:

   Value name: EnablePowerManagement
   Data type: REG_DWORD
   Radix: Hexadecimal
   Value: 0x1

   Possible values are 0x1 (disable power management) and 0x0 (enable it).
   
   

4. Quit Registry Editor.

To activate the new functionality, restart your computer after you apply the hotfix and add the EnablePowerManagement registry value.

To re-enable power management for the device, delete the EnablePowerManagement registry value, and then restart your computer.

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Windows 2000 Service Pack 3.

MORE INFORMATION

For additional information about how to obtain a hotfix for Windows 2000 Datacenter Server, click the article number below to view the article in the Microsoft Knowledge Base:

265173 The Datacenter Program and Windows 2000 Datacenter Server Product

For additional information about how to install multiple hotfixes with only one reboot, click the article number below to view the article in the Microsoft Knowledge Base:

296861 Use QChain.exe to Install Multiple Hotfixes with One Reboot

For additional information about how to install Windows 2000 and Windows 2000 hotfixes at the same time, click the article number below to view the article in the Microsoft Knowledge Base:

249149 Installing Microsoft Windows 2000 and Windows 2000 Hotfixes

Additional query words: kbBaseOS serial

Keywords: kbhotfixserver kbqfe kbbug kbfix kbhardware kbmodem kboswin2000fix kbwin2000presp2fix kbwin2000presp3fix kbwin2000sp3fix KB275042

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