Microsoft confirmed Thursday that it's working on a fix for a battery draining problem on Intel Core Duo-equipped notebooks which it acknowledged to manufacturers seven months ago but had not made public.
In July, Microsoft issued a confidential support document, dubbed KnowledgeBase article KB899179, that outlined the flaw in the Windows XP SP2 USB 2.0 driver. While still not available on Microsoft's public support site, the document has been posted to Slashdot.
The faulty driver doesn't let the notebook enter "sleep" states, where the processor is idled to conserve battery power. "These sleep states are designed, in part, to save battery power," read KB899179. "If an otherwise idle portable computer cannot enter or maintain the processor idle sleep states, the computer uses its battery power more quickly than you expect."
According to tests by Tom's Hardware Guide, which broke the story, the flaw can cut more than an hour from the battery's expected charge lifespan.
KB899179 offered a workaround that involved editing the Windows Registry, but Microsoft is now working on a more practical fix that will involve a BIOS update patch.