Please help. My 2004 Pontiac Sunfire has 27,000 miles. It's loaded with XM radio and all. My problem is that the radio will go to "locked" mode seemingly for no reason during driving. It will come on and go off. I used both sets of keys and it does it with both of them. I had the radio replaced a few days ago at a dealer (which was horrible) and it still has the same problem. Can anyone help? Thanks.