Shut down during login screen

[PhillipRaito]

I got a Asus k451L from 2 years ago, and recently it auto shut down due to over heat. But now it auto shut down at the login screen even it is not hot.

 

[xPhaze]

I would first try booting into safe mode. When the computer is first starting, press and hold the F8 key until you are presented with a black screen with white text giving you the option of entering safe mode. If that loads fine, you can try a system restore or see if you can better figure out what's going on.