I upgraded my ram today from 4GB to 8GB. I used my computer all day long without any issues. Then I noticed I could not open .pdf files with Preview, it would only open in Photoshop. I tried to open .jpg files in Preview with no luck. I figured I would reboot my computer and this is what I got. http://www.youtube.com/watch?v=cKdFTO3o5U4 I removed the ram and no improvement.