Unexpected turn offs – If you keep experiencing unexpected computer, turn offs, you could have bad cable connections, inadequate power supply or defective battery. When your PC overheats, it is also likely to shut down so it can cool.
Beat the problem by ensuring cables are connected properly and checking the fan regularly so you can dust and clean as appropriate. If you are using a laptop, you may want to check the battery; deterioration over time is inevitable and it may be time to have it replaced.