I used to charge from a firewire cable, but am now forced to use a USB. The USB won't charge my iPod (3 gen) from the computer, so I bought a USB power adaptor to charge from the wall, and this doesn't work either. When I plug it in, the apple symbol shows, and then a low battery sign (?) (it's a battery almost empty with an exclamation point next to it). The power adaptor says it will work with my ipod (all iPods with a dock connector...) Any help? Thanks.