I have the same problem – 3 GHz dual Mac Pro, 4GB RAM, Leopard 10.5.7, FCP 6.0.5, QT Pro 7.6, NVIDIA GeForce 8800 GT – could it be something to do with the graphics card? I did have a ATI Radeon before and it produced different artifacts (glitches) on render when hot. This pixelation problem only started after I changed cards…somebody help, this is a nightmare!
Ines Telling
http://www.visavideo.co.uk