If the battery power runs low on a Windows Vista-based portable computer while you are using Windows Media Center, you receive an error message that advises an incorrect way of changing the battery
Consider the following scenario. You have a portable computer that is running Windows Vista. While you are using Windows Media Center on this computer, the computer’s battery power runs low. In this scenario, you receive the following warning message:
Plug in your computer to keep from losing your work, or put your computer to sleep so that you can change the battery
However, this warning message is incorrect. You must not change the battery while the computer is asleep (on standby).
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB955657.