Yikes, that sounds like it could be a lot of things?
You can do a "Search" on this site to see if the topic has
related posts.
Can you please try the following:
On the slide settings, turn off the fade-in and fade-out
settings so that they read as NO FADE.
If the sound is "background sound," you might want to add
this as the sound of a partiicular slide so that you can control
the timing of it.
If the sound is embedded into the slide, then you should be
able to move the sound start and stop in the timeline section at
the top of the slide editing window. In general, ledt click and
drag the entire thing or left click and drag the left end. You can
also double click on the sound object and edit from there.
Not sure this will help you, but I have seen lots of problems
with slide fade-in's and some fade-out's. It appears to me that
sound and fade-in are not always compatible.
Best of luck to you on your project. Please let this board
know if any of the above solves your problems so that others can
benefit.
Joe C.