In one of the books I got on technology (early '00s?) there was an anecdote about a computer at a military facility crashing each night (probably in the 70s or 80s). They brought in a consultant to look at it and after an extended period of time looking for the problem in the code, the consultant was staying late in the data center wracking his brain over the problem.

At 10pm, a janitor came in, unplugged the computer, and plugged in his floor clearer, cleaned the floor, and then when done, unplugged the floor cleaner, and plugged the computer back in.

The consultant then suggested using the outlet on the other wall that had a free outlet (and got a 'difficult to unplug' cover for the outlet with the computer).

The next night he stayed late again and the janitor used the outlet on the other wall.

The consultant then told management that the problem had been solved and it was a buffer problem.