I have a Belkin car charger that worked wonderfully well for my 3rd gen iPod Nanos - we recently upgraded to 5th gen, and now when I try to use the car charger, I get a note saying that my iPod won't charge on that accessory. What changed between generations? and, if I buy a new car charger, how can I be sure that it'll work with my 5th gen Nanos? thanks, Becca