White 02 WS6

Some times when i turn my car off the rear view mirror lights come on which i know they are supposed to. The problem is sometimes the light start to dim on the rear view mirror and if the radio is on, it will buzz out of the speakers. I can wiggle the key while its in the ignition and then the light will come back for a sec and sometimes do it again...Any idea whats going on or how I can fix this?? The car used to chime sometimes and then stop while the car was off but in the position of the ignition on...Any ideas??