To expand on Tom’s message, the first thing I would recommend you try would be to trash the Title 3D preferences – the file is called ‘com.borisfx.Title 3D’, and is located here –
Macintosh HD :: Users :: :: Library :: Preferences
Delete this file with FCP closed, and as a good test, try creating a new Title 3D effect in a new Project or Sequence. If this does not work, go into the Font Book application, disable all but a small handful of primary fonts, and try again.