As for render settings, my normal settings for this project are:

Photorealistic:
Shadows
Reflections
Refractions
Bump
Transparency

Anti-Alias: Best
Object: 0.5
Shadow: 0.5
Sharpness: 75
Ray Depth: 12

720 x 360 - 72dpi
Sequenced TGA

But I have even tested with the following settings and still had problems -
Anti-Alias: None
Object: 4
Shadow: 4

Like I said, these files render slow, but fine in C3, even on slower machines.

Chuck