Microsoft KB Archive/242495

= Troubleshooting Advanced Power Management in Windows 2000 =

Article ID: 242495

Article Last Modified on 10/30/2006

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APPLIES TO


 * Microsoft Windows 2000 Professional Edition

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This article was previously published under Q242495



SUMMARY
This article describes how to troubleshoot Advanced Power Management (APM) issues in Windows 2000.



MORE INFORMATION
Windows 2000 uses various tests to determine whether APM support should be installed. On some computers, APM can cause problems. Symptoms of problems caused by APM may include:
 * An inability to shut down the computer.
 * Problems with devices after resuming from Standby mode.
 * General stability problems with power management.

Before you begin to troubleshoot APM issues, consider or verify the following items:
 * You can use the Hibernate option on all computers, regardless of whether Advanced Configuration and Power Interface (ACPI) or APM support is installed in Windows 2000.
 * Verify that APM is properly enabled in the BIOS, and that any timers for APM are set to a long time-out value so that the setting does not interfere with Windows 2000.
 * Windows 2000 does not support APM on computers with multiple processors.
 * Windows 2000 Server products do not support APM.
 * Windows 2000 does not support custom power buttons.
 * APM in Windows 2000 does not support Standby mode on computers when batteries are not detected (such as on desktop computers). This is a mobile or laptop feature only.
 * Unlike Microsoft Windows 95 and Microsoft Windows 98, Windows 2000 does not support hot-docking on computers with an APM BIOS.
 * Windows 2000 records Standby and Suspend problems in the System event log.
 * Windows 2000 APM reports only a single composite battery, regardless of how many batteries are actually present.

To troubleshoot APM issues:  Use the Apmstat.exe tool to determine the status of APM on the computer. The Apmstat.exe tool is located in the Support/Tools folder on the Windows 2000 CD-ROM. To use the tool, install the Support tools by double-clicking Setup.exe in the Support\Tools folder. Or, you can manually extract the Apmstat.exe file from the Support.cab cabinet file. The Apmstat.exe tool provides an overview of why APM support was or was not installed.

Run the tool by typing the following line:

apmstat -v

The -v switch causes Apmstat.exe to run in Verbose mode. Possible Apmstat.exe output may include:

 This is a multi-processor machine, APM does not work on MP machines, at all. This machine has an APM BIOS on the AutoEnable list, and the APM BIOS appears to be on. APM should have been autoenabled at install. However, APM may have been manually disabled. Check the APM tab in the Power applet in the Control Panel. This machine has an APM BIOS present that looks OK, and it is not on the list of machines known to have APM problems. Check the Power applet in the Control Panel to see if APM is enabled.

The last one of these entries may be displayed on computers that support APM, but on which Windows 2000 cannot determine the status of the computer's APM compliancy.

 Verify that all of the Windows 2000 Windows Driver Model (WDM) drivers running in Windows 2000 are fully compliant. For example, if you are experiencing problems in which the computer stops responding (hangs) or generates "Stop" error messages when you attempt to use any APM features (such as entering or resuming from Standby or Hibernate mode), uninstall or disable any Windows 2000 WDM drivers. If the error message or hanging condition stops occurring, contact the manufacturer of the WDM driver for an updated WDM driver that functions properly with APM in Windows 2000.

NOTE: Microsoft Windows NT 4.0 drivers do not support power management and may not work successfully with requests to go to Standby or Hibernate mode in Windows 2000. Determine how APM was installed. It is important to know if APM was manually enabled, APM was automatically detected and installed, or the computer does not have APM support at all. If you experience problems after manually enabling APM, it may be caused by a BIOS issue. Update the computer's BIOS or disable APM support to resolve the issue. For additional information about how APM support is detected and enabled, click the article number below to view the article in the Microsoft Knowledge Base:

242414 Windows 2000 and Advanced Power Management (APM) Support

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Keywords: kbinfo kbpowerman kbtshoot KB242495

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