I agree with everything that was suggested so far.
This kind of problems are likely to be caused by some faulty hardware.
What is your (detailed) hardware configuration?
Causes can be various: cpu overheating (you have to open the case and also check the thermal grease), bad memory modules, corrupted memory on the video card, bad PSU.
Having some different components to try in your hardware would help.
You should change the components one by one and check the results.