Your Nav is crashing and the graphics/video are being driven by your TV module which will take over if the Nav goes off the bus.

You are using a modded OS, but I also assume you are using a 'backup' DVD or CD map? If so, try using a genuine BMW original.

Other option could be that the Nav Computer is overheating (happened to me in the past and dealer changed out the Nav Computer under warranty) - or you have loaded a slightly corrupt OS image. I very much doub the music CD's had anything to do with it TBH.