Is it possible for you to give us some additional information on this issue. Is this a new build? What components do you have? You tried to boot into safe mode? The most information that we have the greater the chance that we are going to be able to help you out.
With the limited information that you are providing me I would have to guess that this is an issue with PSU. Many times when a PSU (Power Supply Unit) goes bad they can they can start to overheat or shortout with little to no warning. See if you can barrow someones PSU and see if this fixes the problem for you.
Otherwise I would try to boot into safe mode and see if I can run a virus scan and clean any bad files.