Poor electrical supply can really fungoo up a computer. Bad electricity can not only be traced to your house, but it could be bad coming in from the power lines. I have to be extra careful with my computers as Carson City is notorious for having really cruddy power. It took my parents losing two home subwoofers and an amp unit to bad electricity before they invested in surge protectors.

Starting over not only once but twice must be really frustrating. I hope you get the problem fixed soon!