My 2011 MBP (see signature) just died on me, a computer that has been more than adequate for mobile gaming for almost 5 years. I'll be taking it into the Apple Store next week for a prognosis. While using it, the screen went blank, it self initiated a restart, it hangs 50% into startup, the screen goes blank, and then it restarts again and will do this endlessly if I let it. I suspect a graphics problem? On line there are references to "Mac hangs at 50%" and suggesting resetting the NVRAM, tried that no help. Any clues?