Hi Bill-
Yes, I have a HPX500 and thought I was experiencing the same green/yellow shift you are experiencing. I was also posting on the other forum as mentioned above. I am using the Fujinon 17x kit lens.
My problem really boiled down to two main issues. The first was incorrectly setting the lens shading as described on pages 92-94 of the manual. If you leave it on the default, or do the shading incorrectly as I did, you can get seriously ugly results.
The second issue was totally unrelated to the camera, although at first I jumped incorrectly to that conclusion. It had to do with a newly aquired first generation LCD production monitor and the angle of view.
Once I got the shading straightened out, the colors were spot on. Another new owner decided to shift the chroma phase to +2, but that is more of a tweak than large scale adjustment. Lens shading straightened out his green results as well.
I hope this helps.
sn48