Recently installed a new Radeon 9250 and in World of Warcraft I have noticed weird bright spots across the bottom of the screen, the center of them being white and the edges are all spectrum colors. A friend told me this was 'burn-in' and I shouldn't worry about it, but what exactly is burn in? Could it be artifacts? I've heard of them but I don't really know what they are. The monitor is an old CRT, I'm estimating around 8 years --- would it be that? It's been shaking a little bit (the screen) and it had trouble turning on today. Thanks for the help.