Thermal problem... I think your system BIOS is current enough to check for operational temperatures.
Go into your BIOS (see below) and see if there is a section that reports system temperatures and power usage.
Maybe your CPU cooler is inadequate? Or your Power Supply fan is weak or cables are blocking air circulation.
Just my Two-cents.
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How do I get into my computer's Setup (BIOS)
There are some common key functions that can be used to access most brand name computers Setup (BIOS).
Caution: Be careful when you make changes within the Setup (BIOS). Keep a documented list of each change made in case you need to restore a previous setting.
Many computers display instructions on how to access the system Setup (BIOS) while the system is booting. To access the computer's Setup (BIOS), you will need to press a key or a combination of keys before the operating system begins to load. Some common keys are ESC, F1, F2, F10, Ctrl-Del or Del. For more information, check the documentation that came with your computer to find out how to gain access to the computer Setup (BIOS).
Note: If you are still unable to access your computer Setup, please refer to the documentation that came with your computer.
How to access the computer Setup (BIOS) on many brand name computers
Warning: The instructions listed below may vary depending on the make and model of your computer. Iomega® does not assume responsibility for any problems that may occur by using this information. We recommend you use the documentation provided with your computer to access your computer setup and change your parallel port settings. If you have questions, please contact your computer manufacturer.
Dell® computer
To access the Dell Setup (BIOS) utility:
Press the DEL key when rebooting. If the computer is a 486, the F2 key may be used instead.
Dell Latitude
To access the Dell Latitude Setup (BIOS) utility:
Press and hold the F2 key before starting the computer.
IBM® Aptiva
To access the IBM Aptiva Setup (BIOS) utility:
Press the F1 key at restart.
Gateway® 2000 computer
To access the Gateway 2000 Setup (BIOS) utility:
Press the F1 key during reboot.
Some Gateway computers require the F2 key to be pressed
(rather than the F1 key).
Packard Bell® Computer
To access the Packard Bell Setup (BIOS) utility:
Press the F2 key at reboot.
Some Packard Bell computers you may have to press the F1 key.
Micron® Computer
To access the Micron Setup (BIOS) utility:
Press the F2 key at reboot.
CompUSA® computer
To access the CompUSA Setup (BIOS) utility:
Press the F2 key at startup when memory is counting up.
AST® computer
ref: http://www.iomega.com/support/documents/10894.html
To access the AST Setup (BIOS) utility:
Press-down the Ctrl-Alt-Esc keys at the same time.
If on a 486 AST computer, Ctrl-Alt-Del keys may be used instead.
Compaq® computer*
Press the F10 key on boot during the memory count to access the setup or BIOS.