This may be apocryphal, but I recall a story from many years ago of a glitching CRT terminal. The manufacture replaced it with another but the new did the same

This may be apocryphal, but I recall a story from many years ago of a glitching CRT terminal. The manufacture replaced it with another but the new did the same thing so they sent someone to the customers site to see what was going on. That's when the technician discovered that there was a tokamak next door...