I feel your pain.... I have nav and DSP, and mine's done it twice in the last two weeks. I still have a nav display, but it's like someone hit a MUTE button.... no music on radio, cd, cassette or nav wench.... Shut off the engine, start it up and it's back.

If you find the cure, share....

I'm going to clean some connections this weekend and see if that helps.. Dan

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2002 X5 4.6is, Black Sapphire on Black
1997 328is, Black on Gray
2003 SL500, Black on Gray
UH-1H Helicopter, Yellow