LCD monitors are not susceptable to permanent burn-in. Temporary burn-in can be fixed by displaying pure white for a moment.
Has anyone noticed that nearly all TV networks display a permanent logo in the corner of the screen? They don't burn in because the image "jitters" around by a few pixels and people tend to change channels occasionally. Only a sharp-edged static image displayed continously for months or years could even produce a noticeable temporary burn-in on an LCD screen. If a user has a display so wide that there is no room left for even a few pixels of automatic scrolling, and insists on never turning the system off, they could still eliminate all possibility of burn-in by looking at something ELSE on their computer every few weeks