Every morning around 7am, residents of the Welsh village of Aberhosan in the UK noticed that their broadband would fail. The problem went on for 18 months and even a program to replace the broadband cables didn't solve the problem. Finally, broadband engineers combed the village with a spectrum analyzer and found the source of the interference. From the BBC News:
"Our device picked up a large burst of electrical interference in the village, [said engineer Michael Jones].
"It turned out that at 7am every morning the occupant would switch on their old TV which would, in turn, knock out broadband for the entire village."
The TV was found to be emitting a single high-level impulse noise (SHINE), which causes electrical interference in other devices.
Mr Jones said the problem has not returned since the fault was identified.
I hope the villagers chipped in on a new TV for their neighbor.