Try running a long SMART test on it. I know you can do this using smartmontools in Linux. It doesn't give you a progress bar or anything so you have to literally leave it alone for 4 hours or so. SMART will tell you if there really is a problem. It's pretty easy if you have a debian-based distro handy, a LiveCD is fine but you have to stay booted from it for a few hours.
sudo aptitude update
sudo aptitude install smartmontools
sudo smartctl -a /dev/sdX #About your drive
sudo smartctl -t long /dev/sdX #Run a long SMART test.