I've been having a problem with my Droid X for some time now. When the phone has been in use and is hot or even slightly warm, the battery will not charge. I have to leave the phone unused long enough for it to cool down completely - sometimes 5 minutes, sometimes much longer, depending on how hot it got. Then, it will charge usually, although if a text message comes in, an app update launches, or the phone otherwise becomes "active" while on the charger, charging usually stops. I have tried a new battery, and using multiple chargers (including the OEM charger, another charger from the VZW store, another wall mounted USB charger I have, plus a car charger). I took it to the store and they swapped my charger thinking that was the problem, and suggested a new battery, but no improvement. The phone is 20 months old, but other than this charging issue works well and meets my needs. It is obviously out of warranty.
I've seen other posts suggesting the USB charging port could be damaged, but I'm not sure why that would vary based on whether the phone is warm or cold. That result has been very consistent over the past several months - when the phone is active or warm, it won't charge, when it is cold it usually will. Charging from a depleted battery is even more temperamental, but generally similar. The whole thing is very frustrating - any suggestions?