This problem seems to be sort of random. I had the problem, took it to bmw and they replaced the electronics.
A few weeks later i saw the problem again, and then never again.
My best guess is that moisture shorts something out in the electronics. every time i've had this problem the entire front window fogged up right after starting the car.
Just next time this happens to you, check if it's early in the morning when you start the car.
Last edited by JavierBayArea; 12-12-2012 at 12:37 PM.