Originally Posted by InfectionZero
Try resetting your overclock to default clock speed. Overclocking, while very awesome, can produce some funky situations like these.
Yup. Sounds like an overclock gone awry. Once the system has been dialed back to stock, run a memtest on the system, and if that checks out ok, run a chkdsk on the hard drive to fix any problems the O/C may have caused. If the system remains stable, you found your problem. If not, reply back and we can try other ideas too.
A few bucks at a store to test a hard drive? I never trust anyone to test my system, hard drive or otherwise for "just a few bucks".
If you want to test the hard drive, GWSCAN is your friend.