I recently bought a used 7900gtx video card to upgrade from onboard 6150le graphics, I don't recall the dotted lines showing up when I first upgraded but just a while later and It don't happen all the time. Sometimes it will be in the start menu's all programs or on the desktop or on the web when looking at pics, they are not real bad or very many of them. I am just worried they will get worse. When they appear on the desktop I can refresh and they will disappear. I tried older nvidia drivers and still the same thing I ran a short artifact test but it found no errors. Any help would be greatly appreciated. Here's some screen caps.