This is _the_ problem with processing on Windows machines and I can't find
references/fixes for it:
After about 1.5 seconds the audio cuts out with Quicktime playback.
Everything else works fine (capture, video image, etc.) And it's not a
problem on the Mac. I've tried it on a dozen installs on different Windows
boxes and it's always the same. Everything works perfectly except for the
audio disappearing about a second into a video clip playback. I work in a
school and want people to switch over from Max/Jitter and we can't because
of this one issue. (QT 7 under XP with many different machines (Intel,
Pentiums, all of them))

*** This bug has been marked as a duplicate of 277 ***