Simple as this, you got a problem with your harddisk, I had the same problem and i fixed it.

1. Reformat your harddisk.
2. Install a clean copy of XP or windows X
3. Run windows surface scan.
4. Mark bad sectors with western digital Data life guard
tools or any other harddisk tools that suits your
harddisk manufacturer.
4. Install anti virus and spyware blasters.

That's it you are done. Wait for other QLER's to respond too.