[djmcmath]

Update: I pulled the stereo out and had it replaced under warranty -- I had about two weeks left on the warranty period, so I figured it'd be worth the hassle. Same problem. So the stereo itself wasn't the faulted component (most likely).

Totally unrelated to the stereo problem, I've been having intermittent alternator problems. I replaced the battery, because it just wasn't charging well, then I started getting a flickering alternator light, so I replaced the voltage regulator. The flickering alternator light persisted, so I replaced the alternator. The flickering alternator light become more frequent, if anything.

Further investigation showed that the charging terminal under the hood on the right side was heavily corroded. I had thought that was a single-point item, but I discovered that it's actually the connection between the alternator and the battery. So I dismantled that whole connection, cleaned everything up (sandpaper and a file), re-crimped a new connection on, and put it all back together neatly.

And so far so good. The intermittent stereo problem hasn't resurfaced, and the alternator light has stayed out.

In retrospect, it was so obvious that I'm embarrassed to admit I hadn't seen it earlier. #shame Thanks for the ideas, everyone. (But you couldn't have guessed the answer because I omitted a piece of data that I thought wasn't related. My mistake.)

Dan