I just ran into this today, here's the scenario:
I created a slide and included some custom audio as background audio for the slide. The slide only appears in the "Warm-Up" portion of the presentation. However, numerous slides in my "Service" portion also seem to be playing the same background audio, even though I never set that to happen. It happens whenever I do a preview of my presentation, stop the preview to edit a slide, and then return to Preview mode. That slide will start playing the background audio from my slide in the Warm-Up portion of the presentation. It's driving me crazy, as I am concerned that this will happen once I go On Air this Sunday.
Anyone have any ideas?