found this click here
Its same problem as yours but computer shutting down using Spybot.
# Make sure that the fans are running and that dust is cleared from any ventilation ports in the case.
# For desktops (See Caution! below):
* Consider opening the case and checking to make sure the CPU heat sink is not dusty or loose.
* There is a tutorial on cleaning desktop computers here:
o Cleaning the Interior of your PC
# For laptops (See Caution! below):
* If your owner's manual tells you how to open the case (IBM ThinkPads and Dell Inspirons generally do), consider opening the case and checking to make sure the CPU heat sink is not dusty.
* If you have a laptop with one of the one of the following processors:
o Mobile Pentium III-M
o Mobile Pentium 4-M
o Mobile Pentium 4
o Mobile Pentium M / Centrino
o Mobile AMD