what brand of HD are u using?
go the website of your HD and download their test/fix software.
the program/tools from the vendor know more about the hard disk than others.
If it is media problem, in most time, it can be fixed. I have a IBM 30G HD have about may be 1 or 2 percent bad secter. I did low lever format twice, still there. I downloaded a small program called DFT(Disk Fitness Tool) from hitachi(OEM for IBM). I ran the program in Advance mode(test, fix sectoer) for 5 times. Now no more bad secter.