Everytime I select Export/Using QuickTime conversion or Batch Export/Settings, FCP completely shuts down. I have trashed my preferences and uninstalled some FX plugs that were not loading. I have tested out projects and sequences that previously worked with these commands to no avail. I recently used the XSlimmer demo to slim down Final Cut, but I have since restored the backup version.
FYI, I am still able to export via the regular "QuickTime Movie" command.