Computer shutting down midplay

My computer shuts down after a non-specific time when i play this game. The first time it did it i was unable to restart my computer for like a 10-15 minutes, and the second time i could restart the computer instantly after the shutdown.
It does not give me any warnings / error codes / errors it just turns off the computer on a whim.
I don´t think my computer is overheating as i have used more demanding programs for longer periods of time.

I am using a few years old msi gaming laptop.

OS: Win 7 64bit
Processor: Intel i5
Graphics Card: Ati Mobility Radeon HD 5800 Series


Very related to this : http://www.pathofexile.com/forum/view-thread/68140/page/1

EDIT: I now know the reason for the shutdown, it is my gpu overheating due to an unknown reason. This said heating began as soon as i reached the login screen and stopped as soon as i turned off the program.

Chart of the heatings : https://dl.dropbox.com/u/18485762/loltoplel.png

Check your gpu/cpu temperatures. I think your problem is overheating and when that happens computer shutdowns without warnings / error codes.