Agree with zzzzland, go ahead with Microsoft Scandisk or if you
have Norton, the Norton Disk Doctor. Do a complete surface scan.
The system will mark out all unusable bad sectors
Note. If ur hardisk starts to develop bad sectors, and in an
alarming rate (ie, bad sector start to appear once a month,
week,days) be careful, Hardisk is going to crash. THERE IS NO CURE
FOR BAD SECTORS!!! WHY?
Bad sectors are physical problem with the hardisk platters. Causes
are usually created by dropping ur harddisk, subjected to shock,
very old hardisk due to wear and tear over time and sudden power
off (did not do proper power shut down).