Nav Screen does a complete flip out!!!

[abster641]

Driving merrily along and trying to not let the fact that someone else has tried to kill themselves on the beltway all of a sudden my Nav screen starts flipping out. My navigation is still speaking to me through the speakers but the screen is blinking in and out. The Intravee is still working but the screen keeps opening and closing. This continues for a few minutes and none of the buttons would work. I could not turn the system off. Finally, it turns itself off with a message saying the screen has overheated. The dealer can't see me till Tuesday and I have not been in the car since this happened. Any ideas?
Car specification: 2004 X5 with Navigation, Intravee and Sirius module installed. There is no bluetooth module in place.

Thanks!