Binary package hint: pulseaudio
After upgrading jaunty today, pulse (0.9.14-0ubuntu11) broke for me.
When watching a video with mplayer it usually works ok at first, but pausing and resuming sometimes trigger this bug. Rhythmbox has this same problem too. I can not reliably trigger the bug.
When the bug triggers, pulseaudio process consumes >60% cpu and fastforwards playback, while outputting a static noise. (Think analog television badly out of tune). I've had to kill the process to recover.
I have not seen this with previous versions, and I update 3-5 times per week and use sound every day.