I was copying some files over to my external hard disk and suddenly a message popped up saying that some file was open and it could not continue.It asks me whether I want to cancel the operation and I said cancel(The other operation was continue.) After that whenever I plug in the usb into the same computer it does not work. It keeps saying that I need to format the disk to continue. Luckily for me it opened on another computer and am backing up all my data. But now I am wondering why exactly this happened. Is it that the hard disk is weak. Also as an addon I currently use http://www.dtidata.com/windowssurfacescanner/ program to check for bad sectors. Is this the recommended way or is there some other better more reliable way to check if my hard disk is failing? Also could the above problem be because the hard disk is failing? If not why does it happen.Even if the hard disk is interrupted in the middle of a read write cycle doesnt there exist error handling code to enable gracefull recovery?