|Run chkdsk /R. It will do a surface check of the entire drive. It will take hours for a large disk, so pick a time when you don't normally use the system. Maybe overnight.|
If it finds any bad sectors, it might fix(?) them by assigning alternates. But it's not a good sign when bad sectors start showing up. You should make sure that all your backups are up to date, and consider purchasing a replacement hard drive.