This might be obscure, but I have found that RedCine will not render QuickTime files (they come out black) when I have my nVidia Quadro FX 3450 set correctly to Dual View (as per Avid instructions). Meanwhile, RedCine renders out perfectly fine when the card is not set to Dual View (e.g., when monitors are set to Horizontal span). I definitely want my system set to Dual View.

Strange.