I run an older laptop that consists of an ATI A6 processor, and 6670m GPU. What seems apparent from all my shut downs is that MWO is particularly processor heavy. It will tend to run the processor at max speed, and on machines with poor cooling such as a laptop and hot processors, that CPU is going to run hot.
What really fixed it for me was to go into AMD's Catalyst Control Center, and under performance/CPU power, move the CPU processor speeds down a notch. This effectively underclocks the CPU, and thus reduces heat to an acceptable level. At least for myself, the performance drop is hardly noticeable, especially with one notch down. Once I'm done playing MWO, I just crank my CPU sliders back up.
Just wanted to post this in case I'm not the only one having this problem. I'm not sure if other laptops with Nvidia GPU's and Intel Processors have similar features, but it's worth having a look if you are having the same problems I had.
Edited by Sylonce, 09 February 2015 - 06:34 PM.