uh oh. This morning my refurbished i7 2011 27in suddenly gave me a light blue screen. I shut if off, turned it back on and it ran fine for about 5 minutes and did it again. Now after a few boots trying to get it running, on the boot up white screen w the apple on it, it also has about 1 inch wide vertical stripes about 6 inches apart.. then it just goes to a white screen. What does this sound like? It can't be good I know that. help!