Well I thought this is the problem:If you are using the Default HDR image that comes with Cheetah, it has a yellowish (some would call it "warm") impact on most renders in my opinion. The default HDRI is not perfectly white balanced. This is natural byproduct of image based lighting. To get a "neutral" render using an HDR image for lighting, you will need a perfectly neutral HDR.
Well, now, I'm still having problems. I thought it was fixed but it's not. In 5.3 I never had this problem, but since upgrading to 6.3 my renders have been yellowish/reddish a lot. I'm using no area lights, no point lights, etc. I'm lighting directly from the HDRI file, the same HDRI files I was using in 5.3. It's just a yellowish/reddish cast in the render. Anybody know what gives?