Comment 2 for bug 475334

There's a related problem (I don't know how it is related, though): if you set mpd to work with a password from gmpc, the tag browsing (artist/genre browser) functionality stops working (empty lists). If you set the server to work without authentication, the tag browser lists everything again. You can't have both.

I got the clue to this two problems being connected from this thread:
http://www.musicpd.org/forum/index.php?topic=1946.0