"XP" that is without SP1 or SP2 doesn't have USB 2.0 support so that could be the issue (unless you had such and forgot to tell.) Other details would be nice such as if you tried system restore.
Windows XP is the operating system I am using the hard drive is a Western Digital External USB 2.0 80 gig. It was working fine. I defrag it Thursday worked all day and Friday came in on Saturday and got this Windows-Device TIme Out The specifiec I/O operation\device\harddisk\DR7 was not completed before the time-out period expired. The hard drive power up I can hear it crank up and run no strange noises. Windows does not see it I have no icon or anything. Any info would be nice Thank You.