I had a similar problem but with FCP4 on a G4. When I tried srubbing the image would stay still in the canvas and playback was in jumps.
But solved the painful problem. TRY THIS.
1.Make sure that your canvas and viewer are ‘fit to window’ aspect & not on magnification. On the top left corners of each preview you will find 3 tabs. Click the first and select ‘fit to window’.
2.Check your playhead sync under ‘View’ then’Playhead Sync’. You got 4 options: ‘Off’, ‘Follow’ ‘Open’, ‘Gang’. I cant remember which one is the appropraite one. Play around/check user manual.
3. If you have a cam connected check the settings under ‘View’ then ‘External Video’
4. Keep that unlimited RT off.
5. Never give up!
G.Luck.
Lanzi,
Rome, Italy.