Do you have any signs of disk or memory problems on your player? Are you running hijack, using the reservecache flag in config.ini or running third party software?

Yes on Hijack, but nothing else beyond that. No reserves. No signs of hardware failures, at least that I've seen.

Do you use the autovol settings of hijack at all?

Yup, that's probably why the volume drops. The pop from the ram cache running dry could be freaking out the volume adjustment.

It might be a good idea to run a memory test on the unit, just to be safe. Also, you might want to run a manual fsck and not any errors that you might see.

Is there a preferred memory test program? I'll have to go in and play with fsck'ing the disks. My suspicion is that the hardware is all fine as everything does work once it's in steady state, modulo the popping. If there were bad memory or disk, then I'd expect to see much flakier and inconsistent behavior. Hmm... the first and most obvious test is to try some smaller playlists rather than just down-down-down to get everything. I'll try that today on the drive home.