An Outlet in the dining room which had a microwave plugged into it stopped working. I found 120+ volts from hot to ground and 96+ from hot to neutral. Also at one point my "three light tester" showed hot-ground reversed at one point, but also good at another point.
After researching on-line I believed the problem to be an open neutral, possibly in a back stabbed outlet or loose neutral wire nut connection. I started by checking all connections on that particular circuit once I isolated it in the breaker box. I replaced both outlets,connecting to the screws not the backstabs. I also rewired light switches by disconnecting the backstabs and re-attaching to the screws although this step, in hindsight, was probably unnecessary.
Eventually I found a two wire (hot and neutral only) ceiling light fixture in an adjacent laundry room (same breaker in panel box). The plastic fixture box has four Neutral wires plus the neutral light fixture and a ground wire all in a single wire nut. When I removed the ground from the connection of five neutrals (four rolex and one light) the light stopped working and I now have 120V from hot to ground but only 16V hot to neutral at the outlet.
I really don't think I want to rewire the ground back into the neutrals and I am thinking I should continue by checking the neutral set screws on the neutral bar in the panel, but I'm a little stumped about the ground that I disconnected and re-attached to the green nut on the light mounting bracket that spans the plastic ceiling box.
Best Answer
The ground conductors were probably functioning as your neutral return (just not very well) until you disconnected it at the light. So not only do you have an open (or high resistance) neutral wire, but you also have too much resistance in a ground wire. If you've checked all the boxes and terminals for loose connections, you may have a damaged wire in the structure somewhere. The high resistance will cause heat (and risk of fire) if you continue to use the circuit. I would probably contact someone who has access to test equipment that can diagnose the actual in-wall wiring. (like maybe an infrared thermometer to detect a hot spot, or a voltage detector to trace wires in the walls, or at least an ohmmeter)