Just a stab in the dark here... Have you tried to reproduce your problem with the Sudden Motion Sensor feature of your PowerBook disabled? I've had issues with audio playback when this is enabled on the same hardware you mention here.
These settings are persistent across boots.
I played around with HALLab (after building it) for a few minutes.
Pardon my CoreAudio ignorance, but I don't really understand the data
it's giving me or how to interpret it.
Just as Jeff suspected, here's one thing I noticed after playing
around a bit: I did a File>New>New Input Window, clicked on "Start
IO," and watched the Log to see what happened. When the audio
skipped, a corresponding log entry appeared, similar to the following:
449626.252741: overload
Again, no idea what this means, but it's a promising lead.
I'm not sure how to hook into a target app. File>New>New IO Cycle
Telemetry Window didn't give me much luck, either: I couldn't figure
out how to start the monitoring, and no data ever appeared in that
window.
To answer Alex's question: the one that's stuttering is the internal
drive on my 17" PB 1.67GHz with OS 10.4.2. The drive is 100GB, 5400
rpm, and connected via Ultra ATA/100.
Chris