I have been using a protable Hitachi SimplTough 320 GB external drive to store and carry files from my home PC to my office and to client meetings. The drive was working just fine. Now, it lights when plugged in and the drive spins, but Vista won't acknowledge that it's plugged in. The USG connection is integral to the drive, so I cannot detach it. I'm trying to avoid spending hundreds of dollars at a data retrieval supplier. Any suggestions?