If a track stops "writing itself" - abandon it. Start something new.
Then if that new track also reaches the point where it stops writing itself, use the "import song..." feature from the right-click menu and merge the two to something new. - usr
MarC, a new developer from England made a Mp3 Loader that loads Mp3 files as .wav files into the Buzz wavetable. It can also handle VBR mp3 files! This is a very cool tool, but also very Alpha, so if you find any bugs, please let him know.