At my company, a Windows XP Professional Edition user in a nondomain network was having a problem with a program that takes several hours to run to completion. During execution, the program would stop for no apparent reason. I traced the trouble to the hard disks spinning down after about an hour of keyboard and mouse inactivity.
To correct this problem, I went into the Control Panel Power Options applet and selected the Power Schemes tab. XP Pro was defaulting to a power scheme called Portable/Laptop, which wasn't suitable for the user's needs. I clicked the Power schemes drop-down list. There was only one other option, Home/Office Desk, which also wasn't suitable. So, I decided to change the attributes for the Portable/Laptop Power scheme to the following:
After I clicked Apply, I received the error message, Power Policy Manager unable to set policy. Indicates two revision levels are incompatible. This error is documented in the Microsoft article "Error Message: Power Policy Manager Unable to Set Policy. Indicates Two Revision Levels Are Incompatible" (http://support.microsoft.com/?kbid=302713). That article basically says you can't overwrite an existing scheme name, but you can save your new scheme under a new name by using the Save As option.
Armed with this knowledge, I entered the new settings, saved the scheme as Custom Scheme, and exited. I later noticed that the drives were still spinning down, so I went back into the Power Options applet. I saw that Portable/Laptop was again selected in the Power schemes drop-down list. Custom Scheme wasn't even listed.
I wondered whether this problem was an XP user issue. I logged off as the user, then logged back on as Local Administrator. On the Power Schemes tab, I saw not two but six default schemes available. I reviewed this behavior with a Microsoft Product Support Services (PSS) representative, who had a couple of good troubleshooting suggestions. The first suggestion was to try the Msconfig utility to see whether a loaded program was causing the problem. The second suggestion was to try to export the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Controls Folder\PowerCfg registry subkey from a known good XP installation and import it into the problematic PC. I took a look at that subkey on both the problematic PC and a good PC. I noticed that both PCs had the six OEM default profiles as well as several other schemes that had been created but never displayed in the Power schemes drop-down list on the Power Schemes tab. I also saw that the PowerCfg subkey had a ProcessorsPolicies subkey that I didn't want to become familiar with the hard way.
The PSS representative's reference to the PowerCfg subkey and a little digging helped me come up with a solution. First, I accessed the HKEY_USERS\.DEFAULT\Control Panel\PowerCfg subkey. I noticed that it had all six default power schemes with no undesired extraneous schemes. It also had a GlobalPowerPolicy subkey but not the ProcessorsPolicies subkey . I decided to export the HKEY_USERS PowerCfg subkey and put it in place of the HKEY_CURRENT_USER PowerCfg subkey because the HKEY_USERS PowerCfg subkey had all six default schemes, one of which is the desired Always On scheme. Here are the steps to make this switch:
- Export HKEY_USERS\.DEFAULT\Control Panel\PowerCfg and save it as HKUsersPowerCfg.reg.
- Open HKUsersPowerCfg.reg in Notepad. Search for all occurrences of \[HKEY_USERS\.DEFAULT\Control Panel and replace them with \[HKEY_CURRENT_USER\Control Panel.
- Export the existing HKEY_CURRENT_USER\Control Panel\PowerCfg subkey so that you have a backup if needed.
- Delete the existing HKEY_CURRENT_USER\Control Panel\PowerCfg subkey.
- Import the freshly edited HKUsersPowerCfg.reg subkey.
The user now has all six default power schemes available. Interestingly, the Save As option in the Power Schemes tab now actually works.
I noticed this same power scheme problem on another XP Pro PC that was upgraded from Windows 98. Perhaps the problem originates during the upgrade. If your users have been experiencing similar problems, you can use the XP PowerCfg Fix.txt file to help make the necessary registry changes. (Use it at your own risk.) You can download this file from the Windows IT Pro Web site. Replace the .txt extension with the .reg extension.