truncated narrations & premature advance to next slide

I'm attempting to use the narration capability in Powerpoint. I have tried
this with both 2004 and 2008 Powerpoint and on both OS X 10.4 and 10.5 and
seem to have the same problem. My preferred work environment involves OS X
10.4.11 with 2004, but I can use 2008 if I must. I'm telling Powerpoint to
save the narration with each slide, not to link the files. I do not want to
have to use another piece of software to edit my sound files and then
re-insert them back into Powerpoint.

I'll record narration for a slide -- the narration may actually take 1 min
or so and then I pause after talking prior to advancing manually to the next
slide (to ensure nothing gets lost during the slide transition). But what
gets saved is only a portion of the actual narration and then Powerpoint
automatically advances to the next slide. There does not seem to be any
pattern to the duration over which Powerpoint captures the narration -- it
seems to be random, but is almost always incomplete.

Is there some setting I should make to my Powerpoint 2004 program that would
enable it to capture the entire 1-2 min narration for each slide?