I would suggest that it should work without moving the drive as Sandra suggested, but worth trying anyway.
Try doing your regular spyware check etc... could something be stuck in memory from that?
Also, some data may be stuck in memory if the pointer is lost - it may have been a one off incident... believe it or not the sun will make your PC crash once a month on average due to radiation changing a 0 to a 1 in the memory.... strange but true, so you could image it is a one off. Try again normally, and see if you get the same result.
But I do think thats kinda strange...