Well, you can't do anything, save your data soon as possible
Or go to a pc repair center and tell them to repair errors on your hard drive, is cheaper this way.
Are you using windows vista ?
Check your memory , vista includes a memory test program when you`re booting the system from DVD , hope you have one
Another thing could be the temperature... so you should check your cpu temperature in BIOS or with some specific software programs , and if that's a problem , then fix the thermal problems.
Good luck !