My 97 Camaro Convertible will have the radio intermittently cut off and power windows won't work when this happens. I had a new radio put in, but the old one did the same.What's strange is sometimes hitting the power lock button will bring it back on. Some times depressing the brakes will make it go off and releasing the brakes will make it come on. It doesn't matter if I'm driving on a bumpy road or not and tempurature doesn't seem to be a factor, it's just intermittent. Any ideas?