Hey this is kind of weird...but I REALLY recommend getting one of those 3rd party Nyko charge packs with the 2 batteries that are independent from the 360 instead.
I have at least a half dozen 360 battery packs at home that are lemons and I've got friends with the same problem...I don't know what it is, but a lot of the 360 battery packs that require recharging from the system itself just crap out after a while.
I've never had a problem with the Nyko pack I bought last boxing day (and if they're on special again this year, I might buy another just for the batteries) and the batteries seem to last forever once you charge them.
