I am having the exact same problem. On day i started my my car and m F90Bt kept restarting. Tested everything. Noticed that it would only shut off if i went over 30 Mph. I thought the VSS (vehicle Speed Sensor) wire was grounding out somewhere, but checked it and it wasnt. I even took the unit out and checked the connections in the back and everything was fine. after experienting, i unplugged the gps antenna (disabled the gps) and it worked fine again, but with the obvious loss of gps. I'm going to try reflashing the Unit..i'll let you know my progress..