XBox 360 and Media Center

So I have my XBox 360 configured as a media extender and I can access and play the music through the media tab on the little quick dash (brought up by pressing the green XBox button on the controller). However, when I bring up the full Media Center and try to play music from that, it gives me this error: "An error occurred while trying to play your selection." It doesn't matter what I select.

The odd thing is that it will get all the songs and tag information and such (except for album art for some reason), but it still won't play it.

Nothing is blocked in firewalls or anything (at least that I'm aware of). I'm guessing if that was the case then I wouldn't be able to stream the music at all. Any suggestions?

EDIT: I'm uninstalling and setting it up again. This will be my third attempt. It seems it'll work sometimes, then slowly some songs will stop working. It's like they're being moved locally, but they're not. The files aren't even being changed on any level.