Aha. Note to Self: If you're going to have your Zune (or other CD-ripping) software set to automatically rip music CDs as soon as you insert them into the computer, DON'T LEAVE A MUSIC CD in the freakin' drive.
Because every time you start the software, it's going to start ripping the CD for you, and that's only going to screw up anything else you're trying to do. Plus, you could end up with a corrupted folder, where some of the albums' titles don't match their content. (For example, I had what was, ostensibly, a Due South soundtrack album, but when I clicked on it, I saw Mama Cass's greatest hits. Mama Cass's alleged album, meanwhile, contained music by Sarah McLachlan. And so on.
Only some of the albums were fouled up in this way, so I was able to delete them and I'm now ripping them again. It shouldn't take long, now that I realize that for a while there, I had music CDs in BOTH drives and the software was getting a headache trying to deal with it.