When it happens, don’t panic. All you have to do is..
1. Remove all power supply (including the battery)
2. Plug everything back in.
Took me awhile to realize this. I have no idea why this happens. The two times it occurred was when I was running a VM on a RAMDISK and while typing on this page. Not joking.
Addition: Apparently it is due to the processor overheating. It happens when core temperature is near 100 deg C. Weird thing is, the processor used to automatically throttle and scale back the speed at those temperature, but after installation of Windows 8.1, it continued to run on full blast (turboboost) till the internal autoshutdown mechanism kicked in. I don’t know what changed in the backend of Windows, but this will definitely cause a lot of headaches to unsuspecting laptop users.
A solution to this problem is basically to disable Turboboost on your processors to keep the processor temperature below the autoshutdown threshold. This can be achieved by using the ThrottleStop software. Another more permanent solution is to clean the cooling system on your computer. A fully functioning cooling system are designed to and should handle Turboboost temperatures.