have a 2009 sg, recently the radio goes mute, no sound. the rest of the radio still seems to be working. the dial is lit you can change stations, move volume control up and down, but never any sound. Turn the power on radio off and on and it will work everytime. Ten minutes later it will do the same thing. Bumps in the road seem to have no barring on the problem. It also will do the same thing with a cd in it. HELP