An IE question on behalf of my brother.

What could cause IE to render images in 8-bit color even though the machine is set to a 32-bit color mode ?

My brother has a customer who complains that all the images on the Internet are "grainy". From the description she has given him the only explanation that he can come up with is that IE is rendering images in 8-bit color for some reason.

When he emails her an image it displays correctly in Photoshop and Paintbrush. If she drags the same image onto an IE window it becomes grainy. All of the machines at the company the customer works for appear to be similarly effected.

Does anyone have any idea what could be causing this ?