I've used to have the same problem, try what I do;
- on startup of PC, press F10, than you will see a window
- go now on the third tab (or second, not sure)
- there it should say "Hard Disk Self test" (or something similair), if you don't have it, than I don't know how to get the problem,
but I guess that you hard disk is broken cause I had the same problem