I have a 2005 Pontiac Grand Am V6. When I take the key out of the ignition, the radio stays on, which is normal, when I open the door the radio then goes off. Today, I took the key out of the ignition, and the radio, dash lights, head lights and tail lights all stayed on. I tried opening and closing all the doors, even driving it around the block a few times. Nothing seemed to work, so I just disconnected the battery. As soon as I reconnect the battery again, everything comes back on. What is causing this?