If it indeeds shuts down, it probably is heat. Have had that happened to me before. But check to see if the screen just goes blank and the computer is actually still running. I had happen to me with my Gateway FX before. I updated to the latest Nvidia notebook drivers and the screen would just go blank, as in off. I could hear the game running and my gunshots, but no picture per se. It was after alot of troubleshooting until when I reverted back to the Gateway manufacturers drivers that all work well again. I have tried this two times in the past couple of years and have had always the same problem. No problems since then. I just keep my old drivers.