I just bought a refurbished ipod classic 80gb 6th gen; everything about is fine except for one thing: it will charge only on my computer (iMac). The Apple usb chargers I have (3) won't charge it. I read on a thread somewhere else that a user had a similar problem but solved it with a cheapo mains charger wall adaptor; I bought one of these on ebay, and was described as compatible with an ipod classic 80gb/160gb; that didn't work either. Any input on this? Look forward to resolving this irritating little issue.