i used to have an aftermarket receiver from blaupunkt that did this. It would happen randomly all the time, but usually when i came in contact with the faceplate, i have no idea why. I would reach to turn up the volume and the whole unit would power down for about a minute, then came back on. Never figured out why this was happening, just replaced it with a panasonic. It was wierd cuz it would completely power off and you could see the power antenna go down, then back up again.
