Responding to complaints that have popped up on its support forums, Microsoft said this week that it was investigating laptop battery concerns allegedly caused by Windows 7. The problem was first reported on the forum in mid-2009, before Windows 7 shipped.

"We are investigating this issue in conjunction with our hardware partners," a Microsoft statement reads. "The warning received in Windows 7 uses firmware information to determine if battery replacement is needed. We are working with our partners to determine the root cause and will update with information and guidance as it becomes available."

According to the complaints, some Windows Vista or Windows XP laptops that were upgraded or migrated to Windows 7 suddenly exhibit worse-than-usual battery life. Some people also claim that the battery life problem is irreversible: Once it happens, even reverting to Vista or XP doesn't fix things.

But Microsoft says it's most likely a software problem: It suspects that the part of Windows 7 that probes the system for battery-life information is simply misfiring and causing the system to believe that it's running out of battery life much earlier than is really the case.

Reading through the forum, it appears that the problems affect a wide range of notebooks from companies such as Acer, Dell, HP, Samsung, Sony, and Toshiba.