Sounds like zero76 has the right idea. Check the speedwire connections. Plug in a lamp somewhere near what you suspect is the end of the circuit and go around the area hitting the receptacles with your hand. When you hit the one with the loose connection the lamp will flicker.
they have a multiwire circuit (two circuits sharing a neutral) there is a bad neutral connection somewhere. Tell them to immediately uplug the TV and everything else on both of those circuits. If a high wattage item gets plugged into the other circuit, the new tv will recieve more than 120 volts and it will get fried.
