Sounds like the exact same thing that happened to me not too long ago. All in all it took three months, three visits from so called repairmen, and two trips to the repairshop, because the repairmen brought broken components.
But to make a long story short, my PC kept rebooting randomly, i got the same messages that Windows recovered from a fatal error, and in the end it turned out to be a broken mainboard. Once they found that out and replaced it with a new one, things are going smooth again overhere.