I have determined that the lockup problem is definately happening due to heat. If I leave the car outside in the sun and all inside the car heats up, the unit will lockup. Once the unit cools down, all is back to normal. The same thing has happened after a 2 hour trip with the air conditioner on and then stopping to fill up with gas. On restarting the car the Z2 locked up until it cooled down again. Thus without a doubt, the internal heat in the Z2 is causing the lockup wether from outside heat or internal operation heat. Reseting did not work except make me loose my rear view camera input.
