MBP not charging iPod

[lukeoulart]

I bought my 13 MBP earlier this year and so far the only problem I've found is with charging my iPod. I'll leave the iPod plugged into the MBP (via USB) for hours at a time, sometimes overnight, and the battery will never charge above a third. I know this would usually indicate a problem with the iPod, but I've tried charging it on a number of other machines, including other laptops, and a four hour charge will usually fill the battery no problem.

Is this a common problem? Do I need to change some setting on the MBP?

I'd really appreciate any help on this one. Thanks.