Any number of things, but in an effort to take a potshot, without any clarifying info, I'd say the culprit could be a faulty power supply or a intermittent stick of RAM. The specifics (OS, PC type, possible triggering of errors you've noticed, any recent changes made, etc) help us to help you
A forum community dedicated to tech experts and enthusiasts. Come join the discussion about articles, computer security, Mac, Microsoft, Linux, hardware, networking, gaming, reviews, accessories, and more!