Wobbly sound in browsers

[MR ZenWiz]

I noticed yesterday that the sound I'm getting in videos I play in my
browsers (all of them - Chrome, Seamonkey and Firefox) sounds like it
is a sticky tape - it starts and stops, even though the video is fine
and the buffer bar seems to show the data loading much faster than the
playback.

This does not happen with anything I play locally, say with mplayer.

Also, I shut down and restarted all the browsers, and it's still
happening.  I typically only use one at a time, so I don't think it's
interference between them.

I didn't think to look for npviewer running in the background (until
just now), but this is happening at home and I'm at work so, later on
that.

Any suggestions?

Thanks.

MR