Final Cut Pro stops responding when you render a clip that doesn't use the DV codec. The cursor turns into a progress indicator (looks like a colored pinwheel).
This may occur most frequently when you render clips from LiveType because LiveType uses the Animation codec instead of the DV codec.
Solution
Download and install the Final Cut Pro QuickTime Render Plug-in
This is available in document 120263 "Final Cut Pro QuickTime Render Plug-in".