I've had the same problems with chargers. Only 2 out of 5 of my mini-USB chargers works with my HTC TyTN. It definitely seems to be a software issue, because the unit charges fine with these chargers, no matter if they put out 500mA or 1 AMP, when the unit is completely off. Once it is powered on and in standby (screen off) or with screen on, they don't work. I put a note regarding this issue on HTC's wiki 'known problems' page. Hopefully HTC reads their own wiki every once in a while.