Speaker buzz / hiss sound from speaker.
 

I have a 2007 X5 with the premium sound. The other day I unlocked the car and heard a strange noise coming from the rear hatch area of the car. The speaker in the passenger's rear hatch was buzzing very loudly. I turned the car off and the sound did not go away. I drove it across town and tried turning the radio on and off but it did not make any difference. I did hear a slight bit of interference from a radio or something at one time come through all broken up. I parked the car and locked the doors. I could still hear the speaker from outside the car. When I came back to the car it started up fine and the speaker problem was gone. I asked my local BMW dealer about the problem and they said the audio system needed reprogrammed. Well I dropped it off today and they called me to tell me that there is nothing wrong with it and no programming was done. Has anyone had any prblems like this?