|You may have some computer problems, but there is something else that does not compute here. It is fairly typical for the staff computer guru to operate by his or her own rules, but that is acceptable only if this specialist is able to make the computers work. If he or she has mastered the eccentricities without mastering the computer, then you have the worst of both worlds.|
The next time the specialist deciphers what is wrong, you need to decipher what he is saying. If you are given an incomprehensible explanation, tell him that you need more information. You should have an absolutely clear understanding of what he is saying, and you should probably write it down. It is possible that he is making the necessary corrections, and the subsequent problems are the result of poor communication about the changes that he has made.
At the same time, if repairs are truly not being made properly, and if the working relationship with him remains problematic at best, then it is time to discuss the situation with management. Perhaps he needs more training on the technical side as well as in interpersonal relations, since shortcomings in these two areas can cause something other than a computer to get booted.