I just purchased a refurb 24'' 3.06ghz iMac. As soon as I started it up I noticed tiny little dots on the screen in red color. I noticed that different colored dots will appear on the screen depending on what colors are on the screen. A grey background renders green dots, blue - yellow dots, purple or red - red dots. Its frustrating, especially when watching youtube videos, the dots will be clumped up and really affect the viewing. I installed Vista to see if the problem was due to software, but sure enough same thing happens in windows. If I bring it in, will Apple most likely replace it? I've had the computer for 3 days so far. Does anyone know what its caused by. I have another 24'' which doesn't have this problem so i am quite perplexed to say the least!