I would check your RAM, since 10 GB doesn’t sound evenly stacked. We recently had a MacPro with 10 GB of Ram. 4 2Gb modules, and 2 1 GB modules. Our problem was, the High Quality tab on RT Extreme was greyed out. When we removed the 2 1GB modules, we were able to play back at High Quality.
The other thing I’d like to know, is what is your raster size? Is is 1280×720 square pixels, or 1920×1080 square? Likewise, what is your sequence setting? Here’s another thing to try, we had playback issues with AE Pro Res quicktimes that were brought straight into Final Cut. When we pulled them into the Viewer and exported them straight as Pro Res quicktime movies and brought them back in, they played back fine when render. I don’t know why it worked, but it did.
Richard Sanchez
North Hollywood, CA
“We are the facilitators of our own creative evolution.” – Bill Hicks