Just installed Songbird for the first time, won't play any of my music

I just installed Songbird for the first time a few days ago, and it seems to work properly (no error messages or anything) but none of my mp3s will play. I've been digging through all the related topics on this board, but none of the proposed solutions or explanations help.

Exact behavior:

I load my music with the "Import Media" option and it all shows up in the list fine. I select a track and hit play, and the album image updates to a "blank disc" image, but nothing plays and the area of the "bar" that I assume is dedicated to the position slider / progress meter remains blank.

Interestingly, the Shoutcast functionality works and plays music. When I go back to MY music, select a track and hit play it starts playing whatever Shoutcast stream I was listening to again. Pause and play work as expected, but it's always the Shoutcast stream instead of my track, no matter how much I jump around in the interface.

This music comes from a wide variety of sources and is all on a local drive. Right now I've limited it to less than 50 tracks or so until I get this debugged. None of them have unusual characters in the filename. The music plays fine in other players.

System details:

Gentoo Linux (2.6.22-r2 kernel)
Songbird 0.7.0 (no previous installation)
All dependencies from your GStreamer page seem to be satisfied
Plugins: Concerts, DOM Inspector, Javascript Debugger, Last.fm, Songbird Developer Tools (had shoutcast but removed it while troubleshooting)

I really want to get Songbird working. I've been using Amarok a bit lately, but if I have to use something this big (used to use simple stuff like xmms) I want it to support a lot of plug-in possibilities. I've built a few Firefox extensions, so if I can get Songbird working I won't have a big learning curve to hook stuff into it...

Thanks for any help.

Mike