I upgraded my Early 2011 15-inch MBP to Yosemite. Everything works great, but I'm having an intermittent problem with my display. When the computer has been asleep for a long time, the background of the lock screen is scrambled with random blocks of color. The password field is readable, and when I enter my password, the screen is fixed and everything looks right. When I can reproduce the problem, I'll post a screen shot. My MBP has Intel HD Graphics 3000 video and the 2-GHz Intel Core i7 processor. I don't think this is the model with the video people are complaining about. Have you had the same problem? Is there a fix?