Why is Minecraft crashing my laptop?

Okay so, I've had my laptop for a little while and never used to experience crashes during gameplay but now after about 1 hour, 10 minutes or at max 3 hours of playing Minecraft it crashes, this doesn't happen with any other game at all, it can run WoW, SC2, anything like that for as long as it likes without crashing but with Minecraft it just goes. Is Minecraft more CPU intensive or something? (Yes my laptop is very bad and old.)