I have had 3 of these phones. Of course 2 of them were refurbished since I went through the Sim Card Error fiasco on 2 phones before I got a stable one. But all 3 of them seemed to heat up excessively if used for navigation. I contacted HTC support and was told that it was normal since the gps was enabled. I don't necessarily think that should be the answer but most people I know have the same complaint/concern with their various phones. I guess I just gave in. Good luck