Microsft has a page on there site for helping troubleshoot that error (Event ID 18)
Some of the main hardware problems which cause machine check exceptions include:
System bus errors (error communicating between the processor and the motherboard)
Memory errors that may include parity and error correction code (ECC) problems. Error checking ensures that data is stored correctly in the RAM; if information is corrupted, then random errors occur.
Cache errors in the processor; the cache stores important data and code. If this is corrupted, errors often occur.
Poor voltage regulation (i.e. power supply problem, voltage regulator malfunction, capacitor degradation)
Damage due to power spikes
Static damage to the motherboard
Incorrect processor voltage setting in the BIOS (too low or too high)
Permanent motherboard or power supply damage caused by prior overclocking
Excessive temperature caused by insufficient airflow (possibly caused by fan failure or blockage of air inlet/outlet)
Improper BIOS initialization (the BIOS configuring the motherboard or CPU incorrectly)
Installation of a processor that is too much for your motherboard to handle (excessive power requirement, incompatibility)
Defective hardware that may be drawing excessive power or otherwise disrupting proper voltage regulation
Update the BIOS and the drivers for the motherboard chipset.
Update all the hardware drivers, if updates are available from your manufacturer.
Check the temperature inside the computer to make sure your processor and related peripherals are not overheating.
Check the fan on your CPU to make sure it is properly attached to the CPU.
If you have overclocked your CPU, reset your settings to the default settings.
Make sure you power supply fan is working correctly
Also try running memtest and see if it finds any faults.