I think in reference to the 3W neutral sharing, sometimes you have a 3w switch from one circuit landing in a box that has 2-3 switches for another area. Let's say the 3W switch is for the kitchen and includes the load conductors for the kitchen lights, and the other switches in the box are for the living room. Maybe the living room lights are on their own circuit, maybe included with the living room receptacles where this TV is plugged in.
In a moment of weakness, or ignorance, somebody might just tie all the whites together.
Current will follow all paths, so some of the lighting/TV load would be leaking out on the kitchen's neutral.
Having said all that (and patting myself on the back), it's most likely that this has happened before to OP and it's his first go-to on troubleshooting this kind of problem.