Ok this has happened 2 or 3 times in the last month or so

I'll be out with the car radio works fine its on FM one of the presets, I park car shut it off when I restart it I hear a pop through the speakers its now on AM and the clock is a 12:00 the bass treble all go back to default settings .. I dont lose my presets and the 6 little circles are shown in the display but there are no cd's in it ?
all i have to do is switch back to FM set clock bass treble and its ok again
anyone else have this issue

stereo on its way out maybe?

 

It sounds like either there is a short somewhere, or the radio is going out. I can't say I've heard of that before though so I could be completely off