Similar story in the USAF. We transitioned the academy from Banyon Vines to TCP/IP. An entire building wing went offline every day. A team was flown out with a network analyzer. Sure enough, same time every day, the entire wing of the building went offline. Turns out, the person buffing the floor needed a place to plug in the buffer and the only place they could find had this big box with lots of blinky LED's on it, so they unplugged it, buffed the floor and plugged it back in. Half-split troubleshooting may have saved a plane flight.