How to Disable Advanced Power Management for PC Card Modems

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This article was previously published under Q199209

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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 (http://support.microsoft.com/kb/256986/EN-US/ ) Description of the Microsoft Windows Registry

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SUMMARY

This article describes how to disable Advanced Power Management (APM) for PC card modems.

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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.
Under some circumstances, such as when you use an Integrated Services Digital Network (ISDN) PC card modem, it may be necessary for a PC card modem to remain in a power-on state when APM is enabled.

To disable APM for PC card modems, change the EnablePowerManagement DWORD value from 01 00 00 00 to 00 00 00 00 in the following registry key:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\VCOMM

This issue has been reported on an IBM ThinkPad 365 computer. To resolve this issue on this computer, make sure the EnablePowerManagement DWORD value is set to 01 00 00 00.