Have u patch upgraded 11 to the latest version ? (yea, i know, duh). but if that's out of the way, there have been known licensing issues with MAGIX and the MP3 codec title holder. I had presumed they worked all that out because you can use mp3s as audio tracks now (although you really shouldn't). If you still can't, do a render to a *.wav and use an editor to convert to mp3. an extra step, but a step that works, nonetheless. Good luck!