Device: Go 930
Navcore: 9.465

I did a clean navcore install after having problems with Jukebox.
When i try to play a song in the right upper corner the message 'An error occured durning audio playback' shows up and nothing happens.

What is the problem here and how to fix it..?

Hard to say, original Navcore or SE?
Have you tested with a simply single Mp3 files? Quite often the encoding of a file can cause problems.
Things like embedded cover pics, lyrics and so on.
Best is a plain, simple MP3 without any extras in it.