Too many variables to isolate to a specific cause. How much
"stuff" is included in the movie? I mean objects like images,
highlight boxes, buttons, etc.. How large is the project in pixels
(physical size)? How large is the published SWF (digital size)? Is
the problem occurring on just one machine or many? Are you seeing
this when viewing the published project from the web, or from a
local machine? All of the above has to do with available resources,
which I'd think should be eliminated as a suspect first.
Beyond that, does it always "drop out" at
exactly the 10th slide, or just "in the neighborhood" of the
10th slide? What is on the 11th slide that might be causing an
"override" of slide-level audio? Have you tried removing - and
replacing - just the audio on slide #10?
Questions, questions ....