I just got a new black 80GB classic. It seems to work fine, and will charge when plugged into my powerbook with a USB cable. The problem is, it won't charge with a firewire cable when plugged into the wall adapter. This iPod is replacing another which was the same one but it was stolen. That iPod worked with the firewire charger. Does anyone have any advice? Should I send it in for service or is this normal?