I have no proof, but I am 90% sure that is exactly what happened. The stereo was working fine when I brought my car in to the dealer for servicing. The mechanic, not wanting to listen to Mozart (or anything else, for that matter) found the volume knob and turned the volume all the way down to -46.

In doing so, he pressed hard enough on the volume knob to go into the Hijack menu, which was at the "Set Volume Level on Boot" line, apparently the last thing I had ever done in Hijack, years ago. He then pressed the button again, either accidentally or trying to get out of the menu. Bingo! Set volume to current level.

Additionally, as you suggested might be the case, the player was in A/C mode. Since the player lives only in the car (I have no in-house system I could even connect it to) this is not a problem, it seems to work fine that way. But just to be sure, I went further into Hijack and set the Force DC/Car Mode to be DC.

Now all is right with the world.

tanstaafl.