I would try the HD on your computer and scan it. If you get the same problems try formatting the whole drive and start from scratch (It's a bitch but you might have to if the virus scan can't get rid of it.) If you still have the problem get a new HD.
If the problem goes away completely when you hook it to your computer then you've got some other hardware issues.
Sorry if I'm a bit vague, hope it helps a little though.
P.S. Like your sig
