Please give far more details: exact version number of After Effects, operating system, details of footage items (kind of audio file), et cetera.
Are you sure there is not redundant audio associated with your video already and you forgot to tunr off that one? Otherwise provide more info as Todd said, in particular about your audio setup. also tell us, if perhaps you are running other audio tools or music players while working with AE. They might have something to do with stealing and locking the audio device buffer...
Hey, thanks for your response.
I'm pretty sure there was no audio in before because the composition was made from scratch in AE. I had iTunes opened with the proper same song but it wasn't playing at all. Maybe that was it. Anyway the problem was solved after restarting the computer. I think the issue was somewhere in memory usage and caching I guess but Im not IT Im an artist for god's sake. Anyway this bug took me about an hour and half by desperate looking for a solution so it was absolutely serious.
Using 64x mac pro 8core intel OS 10.6.4 btw
once more really thanks. Who knows what a hell happened inside that creepy machine ...and who cares...