Yesterday when I started my car I noticed my display was showing an FM radio station which my daughter had been listetening to earlier but I could not hear any sound. So I turned up the volume and still there was no sound. In fact, none of the radio control buttons on the radio or the steering wheel were working. Surprised, I turned the radio off and on and then everything returned to normal. Half an hour later I made a stop and turned the engine off with the radio still playing on the same station. When I restarted 15 minutes later, the same thing happened again. Any thoughts?