Weird Sound Problem - Sound disappears

[trebbi]

Hi All.

As i couldn't find any threads with the eccact same problems i hope you can help me out with this major problem.

Car is a BMW 330Ci '01
Software version is 3-1/63

The problem is that the sound disappears periodically.
The problem consists on all inputs (radio, tv, navigation, cd) and happens randomly.

It can happen both by driving and hitting a small hole and on smooth new asphalt so the road doesn't appear to have any influence on the problem.

It happens nearly every time i'm driving the car, often many times pr drive.
Sometimes though, it plays for several hours without any problems.

I have noticed that most of time, switching the input (to AM radio and back to FM again, or changing track on the CD player. Just switching radio channel doesn't help) will solve the problem for a moment and the radio will continue playing.

However i also noticed that if the navigation is used, the sound will come back if the navigation gives me directions.
Just after "in 200 meters turn right" - the sound will return and the radio/cd will be playing again (at least for a while).

When listening to cd's and the sound disappears, I can see that the cd keeps playing because it is cycling through the tracks.

On other occasions though, none of the above listed solutions can bring back the sound.
Even shutting down the car helps, next time i start the car there is no sound at all.

It seems like it goes into some kind of mute condition and returns when the mode/input is changed or it gets a new input but i can't figure out
what is going on or what the solution is.

Any help would be greatly appreciated.