Got my 2011 15" 2.2 i7 MBP last month, the one with the 1GB graphics, everything went fine, but 10 minutes ago it seemed like my graphics card was messed up. Colors got milky, gradients didn't flow like they should, and most scary the top left corner turned black, and had green and red squares with pixels in it. Took a screenshot and rebooted, the screenshot doesn't show anything and rebooting fixed it, but I am a bit worried now. What could've caused this problem?