On my iMac I have two users. One for my wife one for me. When I login are colors are fine, just like on my others computers. When logging in with the other account you can hardly see any gradient, all colors are blunt and the contrast is strange. All fonts seem to bleed or are hardly readable. Any ideas?
A couple of things spring to mind immediately: in the Universal Access system preference (Apple Menu>System Preferences…) there is a setting for enhancing the contrast, check that the slider is on "Normal".
Otherwise go to the Display system preference and look at the Color tab. There are various color profiles there, see if the profile for you wife is the same as yours.