Right after I installed a fresh copy of Windows 7, I synced with my DropBox account that contains all of my music and added the directory to Windows Media Player 12. I now have a strange track that really isn't a track at all. It's grouped under "Unknown Artist" and has absolutely no text. The only reason I know it's there is because it highlights on mouse-over. Double-clicking on it does nothing. When the song before it ends, Windows Media Player stops playing altogether until I choose a different song (it should continue to play the next song on its own). When I try to delete this mysterious track, nothing happens. I've cleared my library and re-imported everything, but this empty track keeps appearing. I have also checked my Music directory and there is no empty MP3.

What is going on here?