I just noticed this today. I was using the Navigation in the phone in the car while it was being charged. The charger was working fine, then after a while it wasn't charging anymore. I noticed a blinking red light at the top of the phone. Normally when it's charging it's just solid red. The phone definitely felt pretty hot. It was fairly hot in the car, and the sun was shining through the windows making it even hotter. Later on when the phone was cooled, the charging continued to work, but then again stopped after about 10 minutes. Even after I got home, I tried charging on a regular charger and it still wouldn't charge until cooled down. This is a real problem if I need the Navigation for a long period. Has anyone else noticed this?