I just got my x920bt installed yesterday and since installation, the ATT will randomly come on and off. I got it "professionally" installed and they are arguing with me saying that it could be a defective unit. I personally think that there is something wrong with mute wire that they installed because when I jiggle the ipod wire it will go away and come back and go away again. It's very annoying because I can't turn the volume up or down. Pls help. Is it a defective unit or bad installation of the wires?

ATT is the mute command, have then check their wiring INCLUDING to any steering wheel control adapters.

I have the exact same problem with my X930BT. I installed it myself, and I'm certain all connections are correct. I'm going to cute the Mute wire and see if it stops the problem.