iPOD WON'T TURN ON OR CHARGE

I've been using my iPod with the USB input on my new Honda Civic. It was specifically made for iPod, and my model (120GB) meets the compatibility requirements. All was working perfectly until tonight when the dashboard simply displayed the word "unsupported". I tried unsuccessfully to turn on the device manually, but nothing happened. I thought maybe it needed to be charged, although the dealer told me it would charge while connected to the car. However after an hour in the cradle at home and a half-hour connected to this computer, it still won't turn on. When plugged into the computer I heard the little USB connect sound, but the device doesn't show up in iTunes or as a drive on my PC. What happened, and how do I fix it?