Motorola Droid X :: Battery Discharging While Plugged In?

Ok, so just checking if there is any explanation other than a hardware problem here. I received my second refurb today after my first one arrived with obvious hardware problems and I had to send it back. Twice so far, while plugged in to the AC wall charger, my battery has started discharging. This is with the Motorola wall charger and Motorola extended battery. One time I was using the phone when this happened and the other I was not - it was just sitting there with nothing happening on it but with the screen on and plugged in.

This has never happened before, so if it is a hardware problem, it would be much more likely the "new" phone rather than the battery. I don't want to go through the replacement process a third time and lose even more time without a functioning phone if this could potentially be caused by something else. They said they will not send me a new (non-refurb) phone, no matter how many problems I have and no matter how many broken "certified like new" phones they send me. Doing a search on this, all I found were posts about car chargers not providing enough power with Navigator in use, which does not apply to my case. I really want this not to be a hardware problem with the phone since they will just send me yet another untested, broken refurb, so I'm just grasping for straws I guess despite the obvious.