Hello... I have a 2002 BMW X5 ... And recently, when I start the car, the Navigation screen will not come up (all I get is a blank screen), and the radio would work for 2 minutes and then turn off... I checked the wiring for the Nav screen and MK III system (in the trunk), and everything seems to check out (no cross wirings or lose wires)...Any ideas what it may be? Thanks

Maz