I'm running Windows 7 on a 27" iMac using an ATI Radeon HD4850 graphics card.
The problem: rather than smooth gradients between colors, the graphics are "stepped" or striated. ie. rather than a grayscale gradient smoothly transitioning from black to white, it steps through a series of gray tones from black to white.
Using ATI's Catalyst control center, I can change the color quality from High (32-bit) to Medium (16-bit) and this affects the gradient, but is still not a smooth transition.
On the Mac OS side of the machine the graphics are beautiful.
I've tried everything and called everyone...please help me.