Terry, It really isn't the color balance. The M9 has heavy vignette with some wide angles that is not just in the corners. Cornerfix is a program where you build a profile for a specific lens (and specific vignette pattern) by shooting a white target. Cornerfix analyzes the target and subtracts that vignette pattern from the photo. In the case of Michael's photo, the vignette was magenta (thus causing the change in color).
If you have a lens that always vignettes, check out Cornerfix...it is free!