I have had a 3 Gs since November. Last week I started to receive a random error message saying "This device does not support charging by this accessory". I always use the charger provided with the phone itself. I tried a alternative cord (from a friends 3 Gs) and it still came up. I also cleaned the connection leads of the charger and cord with compressed air and still the messages appear. When the message appears I unplug the cord, plug it back in and it begins to charge. The other night my battery level was at 6% and I plugged it in with no problem and it indicated it was charging. Sometime during the night the message must have appeared and when I woke up my phone was dead. Any ideas on the cause of the error?