Hi guys, I'm new to the forum. I am having a problem with an IMac. I have been using it without any issues until recently. When I am using the Imac and I move windows around or re-size the windows I am using I get pixels the light up neon green, black and red. If I move my mouse pointer over the pixel it goes away but then when the mouse moves away, it reappears. If I drag one of my windows toward the pixels, they disappear before the window gets to them but then reappear in different locations when the window moves away. I recently (about 2 months ago) upgrade my RAM with an additional 4GB for a total of 8GB. I did not have any problems after the memory upgrade. I already tried removing the RAM that was installed with the upgrade, leaving only the original RAM in, but that does not change anything. The pixels still appear. I even tested it with each RAM module individually, but it does not make a difference. Model Name: iMac Model Identifier: iMac12,1 Processor: Intel Core i5 2.5GHz Memory: 4 x 2GB DDR3 1333 Hard drive: 500GB I am running Mac OS 10.6.8 I don't know what else to do, any help would be greatly appreciated.