Shoutbox

Hey all

Wonder if anyone can provide an answer or solution to the following problem.  We have a computer from a friend who windows are trailing i.e. if you move it around the screen, it's like having trail on the mouse pointer. But if you move it downwards, it like a constant refresh (before anyone starts, I know that the screen refreshes). The thing is that icons move smoothly. Any reason why this would be happening?

Thanks in advance