After playing a group of mp3s in foobar a few times, I changed their artist tags using another program. Then, upon reloading them in foobar, the artist tags were overwritten with what was there previously. What is this "feature" and how do I turn it off?

Have you tried Right Click --> Properties --> reload info from file?

HTH.

Alessandro

Yes, I've tried that, but that doesn't work because as soon as the file is loaded, the tags themselves, within the file, are overwritten with info from the database.

Mmmh, I suspect the other program writes, for example, ID3v2 tags and in foobar you are seeing, for example, ID3v1 tags.

Dunno for your tagging program, but in foobar you can check that in Preferences --> Playback --> Input --> Standard inputs.

HTH.

Alessandro