The obvious quick fix is to not leave your computer on for two or three days at a time. In fact, I’d give you this advice even if you weren’t having this problem. Windows tends to get unstable over time, and a reboot refreshes it. Besides, leaving the computer on all the time wastes electricity.

You should either shut it down or hibernate it at the end of every workday. Hibernating the computer won’t refresh Windows the way a full boot does, but it’s faster and lets you start the day exactly where you left off. From the hardware’s point of view (and I suspect you’ve got a hardware problem), there’s no difference between shutting down and hibernating a PC.

Lincoln Spector, PCWorld