I have a 10 GB iPod w/ the 1.2 software on it. I connect the iPod then run the 1.2.1 updater. It says that the thing isn't mounted, but it IS! It unmounts immediately before it gives me that ...

Apple say "After you've de-authorized and reauthorized your computer, open iTunes, select your iPod, and choose Update iPod from the File menu. If that doesn't resolve the issue, try restoring ...