Microsoft KB Archive/254954

= Cannot Start Modems Tool in Control Panel =

Article ID: 254954

Article Last Modified on 12/21/2004

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APPLIES TO


 * Microsoft BackOffice Small Business Server 4.0
 * Microsoft BackOffice Small Business Server 4.0a
 * Microsoft BackOffice Small Business Server 4.5
 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows 98 Standard Edition
 * Microsoft Windows 95

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This article was previously published under Q254954



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
You may be unable to start the Modems tool in Control Panel. When you double-click the Modems icon, your mouse pointer may change to an hourglass shortly and then disappear. The Modem Properties dialog box does not open and no error messages appear on the screen or in Event Viewer.

The same behavior occurs if you double-click the Telephony icon in Control Panel, click Telephony Drivers, click Unimodem Service Provider, and then click Configure.

In addition, you cannot open the Modem Properties dialog box using the following commands:

control modem.cpl

rundll32.exe shell32.dll,Control_RunDLL modem.cpl

NOTE: The second command is case sensitive. Type it exactly as it is shown.



CAUSE
This behavior can occur in Windows NT and Small Business Server because of any of the following reasons:  The %SystemRoot%\System32\Modem.cpl file is missing or damaged. The %SystemRoot%\System32\Modem.cpl file has incorrect permissions. The following registry key is missing or damaged:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Class\{4D36E96D-E325-11CE-BFC1-08002BE10318}



This behavior can also occur for Windows 95 and Windows 98 if the %Windir%\System\Modem.cpl file or the %Windir%\System\Tapi.dll file is missing or damaged.



RESOLUTION
To resolve this issue, use the appropriate method.

Missing or Damaged %SystemRoot%\System32\Modem.cpl File
If the %SystemRoot%\System32\Modem.cpl file is missing or damaged, expand the Modem.cpl file from the Microsoft Windows NT 4.0 CD-ROM. For example, to expand the Modem.cpl file from the Windows NT 4.0 CD-ROM into the C:\Winnt\System32 folder, type the following command:

expand d:\i386\modem.cp_ c:\winnt\system32\modem.cpl

Missing or Damaged %Windir%\System\Modem.cpl or %Windir%\System\Tapi.dll File
If the %Windir%\System\Modem.cpl or %Windir%\System\Tapi.dll file is missing or damaged, extract a new copy of Modem.cpl and Tapi.dll per the following methods:

Method 1
For Windows 95, use the EXTRACT command per Knowledge Base article Q129605 to extract these files to your %Windir%\System directory. To view this article in the Microsoft Knowledge Base click the article number below:

129605 How to Extract Original Compressed Windows Files

You can extract the Modem.cpl file from one of the following locations:
 * The Win95_07.cab file on the Windows 95 retail CD-ROM.
 * The Win95_11.cab file on the Windows 95 original equipment manufacturer Service Release 2 (OSR2) CD-ROM.

You can extract theTapi.dll file from one of the following locations:
 * The Win95_11.cab file on the Windows 95 retail CD-ROM.
 * The Win95_17.cab file on the Windows 95 OSR2 CD-ROM.

Method 2
For Windows 98, use the System File Check utility to extract these files per Knowledge Base article Q129605. To view this article in the Microsoft Knowledge Base click the article number below:

129605 How to Extract Original Compressed Windows Files

Incorrect Permissions for the %SystemRoot%\System32\Modem.cpl File
If the %SystemRoot%\System32\Modem.cpl file has incorrect permissions, change the file permissions to the following information:

Damaged or missing Registry Key
Use the steps below if the following registry key is damaged or missing:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Class\{4D36E96D-E325-11CE-BFC1-08002BE10318}

NOTE: The following steps describe how to re-create the entire key if it has been deleted. If the key exists, verify that the values defined for it are correct.

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.

 Start Registry Editor (Regedt32.exe). Locate the following registry key:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Class

</li> On the Edit menu, click Add Key, and then add the following registry key (including the braces):

Key Name: {4D36E96D-E325-11CE-BFC1-08002BE10318}

</li> Click OK.</li> Click the newly added key. On the Edit menu, click Add Value, and then add the following registry value:

Value Name: Installer32

Data Type: REG_SZ

String: Modem.Cpl,ClassInstall32

</li> Repeat step 5 to add the following registry values:

Value Name: Icon

Data Type: REG_SZ

String: 0

Value Name: Default Service

Data Type: REG_SZ

String: Modem

Value Name: Class

Data Type: REG_SZ

String: Modem

Value Name: <No Name>

Data Type: REG_SZ

String: Modem

</li> Quit Registry Editor.</li></ol>

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