I noticed that in 2.0b7, it considers any MP3 with album art stored in it to be an "invalid MP3 file". Almost my whole collection has album art in it, so until this gets fixed, I will be using 1.02 which plays them no problem. I created these files with Music Match Jukebox and if I clear the album art out of a file, it will play fine on 2.0b7.