Leo says it's likely overheating. There could also be a memory leak of a video driver. Updating his driver will likely solve the issue. He should make sure the fans are working, too. He can also get a laptop cooler that will run fans over the bottom of his laptop. They're pretty cheap.
The chatroom also says that going into his laptop settings and limiting CPU performance to 80% and turning the frame rate down will help guard against it as well.