Although today I am using a different solution (SpeedFan), it is actually very similar to the one given below...
I found this helpful advice by JimmyT1988 at kioskea.net:
-This is to avoid your cpu being damaged.Jimmy agrees with me that buying a cooler for a laptop is the way to go. If that was the reason for my laptop turning off and on repeatedly, the temperature must have gone up pretty fast! Maybe in a week's time, enough dust has collected to cause overheating??
You can check if this is happening to you by downloading "coreTemp":
32Bit Windows http://www.alcpu.com/CoreTemp/CoreTemp32.zip
64Bit Windows http://www.alcpu.com/CoreTemp/CoreTemp64.zip
If the temperature is 90 degrees during your gameplay or infact if it is around 75 degrees whilst just using your computer... This is probably the issue you are coming across.
Buy a cooler for laptop
I downloaded CoreTemp, the 32Bit Windows Version. I installed CoreTemp and it works superb. I keep it in my system tray. My temperatures vary between 56 C and 60 C and I set it so that it puts my laptop to sleep if the temperature reaches 90 C. By default it will not send computer to sleep or shut down in case of overheating. You can tweak the settings to change the display to Fahrenheit. If you just want to check the temperatures you do not need to change anything and just stick with the defaults.
Laptop turning on and off repeatedly, won't boot. Solved!
Protect your laptop in style: Buy a cooler for a laptop.
I also found Speedfan, and I like that too. It can show and regulate fan speeds, and shows hard disk temperature as well.