One of the teachers at the school I support has a Dell Latitude E5500 and about 3/4 of the desktop shows just fine, but the right 1/4 shows whatever was on there last, like it's not refreshing (yes I tried refreshing the screen). For example if I open up Internet Explorer then minimize it the left 3/4 minimizes, but the right 1/4 stays pulled up.

If I change the screen resolution to 800x600, it works perfectly fine. The sceen works together and has no problems.

The only way I have found to get rid of this is to reload the laptop. How can I resolve this permanently?