I have a 5+ year old MBP running 10.8.4. It's a 15" 3,1 or 4,1. Normally, I run it with a dual monitor setup with an external monitor. I've done this for years A little while ago, I was using it and its 6 mb of RAM were pretty much fully used, as if often the case. While watching a YouTube video, the external monitor lost its image, became black as if it were turned off. The MBP monitor retained its display, but I couldn't interact with it anymore. Keyboard input was ignored. The mouse cursor moved around the screen, but clicks didn't do anything. Next to the mouse cursor was a square artifact with some black lines as a part of it. You can see what that looks like in the attached .jpg. So I powered down by disconnecting the power cable and the battery. After a few minutes, I tried to restart, but couldn't get past the white screen with the Apple logo on it. Every minute or so, I'd get a text message in multiple languages that said something about shutting down improperly and hitting any key or waiting to restart. But I couldn't restart. It just looped though this. I turned it off again and waited another 30 minutes or so. This time, I got to the login screen. I chose a user and entered the password. I got a similar message, but this time, it was in a message box instead of on the white screen. But I couldn't really get past that. The OS didn't fully boot and I never got past the screen you can see in the attached .jpg. The blue flare in the .jpg, btw, was something I added to hide the user name. The rest of the image is as it was. I'm taking it to the Apple Store tomorrow, but I'm wondering if anything is obvious about what this might be. I'm mostly backed up, but not completely and there are some things I'm hoping to get off of the hard drive, even if the machine is toast. Any thoughts would be appreciated.