I'm aware this bug is out, I think I just realized what is the cause.
An audio wich has been set to sync in stream plays niceley on the timeline, until you move the red bar on top of the timeline to change from one frame to another, this messes up with the audio and strangely makes it to be synced as an Event. If you close an open flash the problem is solved until you agani move the red bar on top with the mouse.
Or at least that happens to me.
I hope this was of any help to help debbug this... it's an awfull thing...