Hello...
Check what make/model is HDD.
Visit manufacturer's Web Site, download diagnostic tools and test your HDD for possible bad sectors.
Or
Download MHDD 4.6 from here:
http://hddguru.com/content/en/software/2005.10.02-MHDD/
You might have bad sectors on HDD on which are system files.
Also, if you have Operating system installation CD, you could run CHKDSK /R
in Recovery Console but lets first test HDD :D
Keep us posted...