The radio in my Volvo shut off and the seat belt chime won't go away!?

I have a 1989 Volvo 240 Station Wagon. Everything was working fine and all of a sudden the radio turned off and the seatbelt chime started. For the next 3 miles the seat belt chime would not turn off! My seat belt was on and all the doors were shut. I could not get the radio to turn on either. I turned off the car and started it again four separate times already and I have the same problem. I can't seem to figure this one out. Thanks for your help.