I have tried all posted solutions about this topic, but none seem to be successful. I have a feeling that my computer is running way too hot and that is why it is shutting down.
It has always been a problem that under Ubuntu (under Windows it works fine), the power consumption is terrible and it is always very hot and all CPU's run at 100% (without any applications actually taking up the processing power, like immediately after start-up).
I have a standard Samsung q430 with a Nvidia GeForce 310M graphics card, and an Intel Core i3-350M. I have seen that it may be a graphics driver issue.
Also, I have tried installing bumblebee and it really messed with unity and many other applications, so that is not really an option for me. Here is a screenshot