Wall "A" has a switch that controls the light on the ceiling fan. Wall "B" has an outlet used by TV and cable box. Wall "C" has a switch that controls the light on the ceiling fan - alongside a switch controlling just the ceiling fan.
(There are other outlets in the room and, at least, two other rooms on this circuit but I haven't noticed any connection between those and this issue.)
When TV and ceiling fan are on, turning OFF the fan causes the TV to go black and silent for about three seconds before recovering. The TV's power indicator light stays on during the outage.
The house is 18 yrs. old. I've lived here 15 and this just started in the last 2-3 months.
If anyone recognizes the problem and can offer a remedy, I would be very appreciative.