canvas freeze

This is a new problem since we've converted to FCP4... unless we're playing a clip, the canvas is frozen in the last place it stopped. If we click anywhere in the timeline, there is no change in the canvas unless we physically play the clip again. It changes in the external monitor, but not on the canvas. If we restart the application it does work for the first couple of plays, but after that... nothing.

This has become a particular problem when we're color correcting because the canvas doesn't show the updated changes until it's rendered and playing. Help! Help! Help!