It could be due to following reasons :
r virus
It's possible for your computer to be infected with a virus that is designed to shut down your computer or turn it off. If your computer seems to be turning off when executing a certain program at specific times in the day, it could be infected.
If you believe your computer may be infected with a virus or are uncertain if your computer is infected with a virus, make sure your virus scanner definitions are up to date. Additional information about checking this can be found in document CH000533.
Issue with operating system
If after following each of the above recommendations your computer still continues to reboot, it is likely that you are experiencing a Microsoft Windows operating system related issue that cannot be explained. To help make sure this is the case, please try the below steps.
1. Reboot the computer and enter CMOS setup as the computer is booting. If you are not familiar with how to enter CMOS, please read through document CH000192.
2. After you have loaded the computer in CMOS setup, let the computer sit.
If the computer does not turn off while letting the computer sit in CMOS, it is likely that you are in fact experiencing an issue with Microsoft Windows or your operating system and it is recommend that if you have followed all of the above recommendations that you reinstall your version of Microsoft Windows. Additional information about erasing the computer and starting over can be found on document CH000186.
Other failing hardware
If after reinstalling your operating system, or during the installation of your operating system, your computer turns off abnormally, it is very likely that other hardware is failing in the computer. Often this is RAM, CPU, Motherboard, and/or Power Supply (in that order).
If you have extra available parts or have a friend or co-worker with a similar configuration that is willing to allow you to test their hardware in your computer, try swapping these parts to determine if they are At Fault. Otherwise, you will need to have the computer serviced.
Most likely cause is the power supply. Second thing to check would be the motherboard.
Go into computer set up, or control panel and turn off auto shut down or automatic timeout. or, change the time to a longer time, so it only shuts down after say, 1 hour if not used.
throw it off a cliff and buy a new one works for me but no seriously normally for me it is the power supply that causes this problem
turning the computer off
Shutting down means closing or turning off. For instance, when you turn off your computer, you shut it down. When a circus shuts down it's closing.
Turning it off
no you are shutting the coumpter down whats the point?
Yes, it should stop all shutting down actions by your computer if the system is overheating.
Have you tried shutting down all programs, then shutting down and re-starting your computer ?
No.
many reasons but just scan your computer to be on the safeside
You have a virus. Or it is continuously overheating?
Using the "start" button to shut down your computer gives your system a "heads up", if you will, that you are shutting it down. Shutting a computer down abruptly could be destructive to the system if you shut it down in the middle of an important process.
When my computer would unexpectedly shut down on its own it turned out that the processor fan was bad and the computer was shutting down due to the processor overheating.
Re-booting your computer will refresh everything without shutting it down completely.