Have you tried powering down, then powering back up with the USB cable plugged in? Before I switched from USB to firewire, my PC wouldn't recognize the JB3 after plugging in the USB cable unless I powered off and on again.
Also, if you don't want to deal with tech support just yet, check out the user forums at Notmad. I forget the URL, but it's in the Archival Info section, JB3 Info thread.