treadmill shuts down after 5-10 min when in use with someone walking or running, it does not loose power it resets. It will start back up when you press restart in 5 min it happens again. If nobody is walking or running on it when in use it does not shut down. The deck is good and the is good and they were waxed 2 weeks ago. star trac pro s treadmill. what's wrong? please help !