You must tell us WHEN exactly this happens, like in map load or inside play or when you do something unique. I can´t help you, but in my comp I had same problem, but I added another fan and everithing was ok , but i guess that is not your problem...
And your warcraft NEVER crash like this? If soo look in map if there arent any frong placer sounds/textures/models, ect. Or if there is not any abilitie set to negative value.
I had the same problem with my first ROC map, i had no imported models, no negative values, no sounds, not even triggers! (notice it was my first map ) I have no idea what caused this and i didn't bother checking it out couz the map wasn't very good anyway, but something wierd is it and i don't think it's something with the computer couz i have much more advanced maps that works brilliant. Try to check your map after things that might've caused it, and remove things you've added recently to find what's wrong.
, but i guess that is not your problem...