I think this only applies to PPT 2002 or later.
After inserting the sound file make sure it is set to
"start from the beginning" and it usually helps to have
"stop after 1 slide" clicked.
It's also easier if you don't have it play automatically.
Leave the speaker icon on the slide and put another symbol or
action button beneath it, e.g. <-- <--. which I'll call the rewind button.
Select the speaker icon and in custom animation, choose
sound actions, pause, under timing select triggers and make
sure the speaker icon is set as the trigger
Select the <-- or rewind button and choose
sound actions, play. under timing select triggers and make
sure the rewind button is set as the trigger.
So what happens is if you hit the rewind button
it plays from the beginning
if you hit the speaker icon, the sound stops, hit it again
and the sound starts from where it stopped.
Hit the buttons in any order and you'll get what you expect.
Pete