A user says that no matter what image is displayed on her LCD desktop display, she can always see an outline of another image that never changes. What can you do to solve the problem?

With artifacts, you can see the outlines of a different image no matter what is on your screen. That image has been "burned" into the display (also known as burn-in) and will not be removed. The only option is to replace the screen. Burnin is another term for image persistence or ghosting.