seat belt indicator light

I have a 1994 6-cylinder 626 (great car) with 128k miles and the seat belt indicator lamp has started coming on occasionally. I always where the seatbelt, so it is always engaged. I've unplugged the harness under the seat, but it still comes on while driving, then turns off. One day last week, the dinging came on and wouldn't stop even after the car was turned off. A couple times the rear defroster indicator light came on by itself, so I pushed in the rear defroster button to make it go off. Now its driving me nuts since the seat belt light comes on and goes off again all the time! Does is have a short somewhere? Anybody have any ideas?