04 E250 Radio/Dome Light Problem

[Wranglerr]

Today my radio came on by itself after the dashboard started beeping. The engine was off and the key was in my pocket. I was in the side door getting supplies. The dome lights went out and would not come back on. I started the engine, turned it off, opened and closed doors, fooled with the ignition and steering wheel, finally disconnected the battery while I worked. A couple hours later I connected the battery and drove. It ran fine with no problems but when I turned the engine off, the radio stayed on still. The dashboard displayed CHECK GUAGES and CHECK FUEL CAP. My mechanic has the van right now and they don't have a clue what's going on. Of course, just as I pulled into their lot and turned the key off, everything went back to normal. Something similar happened about 6 months ago, the radio would go on and off when I turned the key off and opened the door, the guages would go crazy and the same messages would come up. I have a ford factory radio, power locks and windows with factory remote keyless entry.

ANY IDEAS?! I need my van for work! Thanks!!