Render Error in AE CS6

Question

I'm trying to export a TIFF sequence from AE and I'm running into a render error.  It's a blue screen shot that was keyed using Magic Bullet's Primatte Keyer plugin.  The foreground is a RAW image sequence from a Nikon D800 (.nef 7360 x 4912) and the background is a RAW image from a Canon 5D (.cr2 5616 x 3744).  My frame size is 4096 x 2160.
The shot is supposed to look like this:
But AE exports TIFFs that look like this:
I tried swapping in a TIFF and a JPEG for the background but ran into the same error.  I'm almost certain the error is due to the fact that I'm using such large RAW images and AE is having a problem with them.  I also need to work in RAW for various reason but mainly for the final output so replacing the images with TIFFs or JPEGs isn't an option.  Does anyone have any suggestions on how I can get this to render?
Here are m computers specs:

Answer 1

replacing the images with TIFFs or JPEGs isn't an option.
Why not? Perhaps you might consider an alternate workflow, regardless:
http://prolost.com/blog/2012/12/19/lets-cook.html
If Stu uses these workflows, I'm sure they would work for you. Otehrwise you might wish to check your Primatte plug-in and do the key at a different bit-depth. This looks like 32bit artifacts from the keyer due to a bad color space conversion...
Mylenium