|Heat is a frequent cause of shutting down in laptops. Make sure none of the vents on the side of, or underneath the laptop are blocked or covered. Also, the exhaust fins on the CPU heat sink often get clogged up with fluff.|
If this is the root of your problem there will be poor airflow at the air vent. If heat is the cause and there is no fluff, the fan may not be spinning at full speed if at all when it should be.
If it is a heat problem, it needs to be rectified before it causes the CPU to fail.
Computers... designed to entertain,help with work but most of all to frustrate you!