I am no electrician, like you I can use a meter.
I work for Ma Bell, and I can tell you an open neutral can cause you some crazy problems.
The electrons are going to find a source to ground. The power lines will sometimes go open due to squirrels, normal wear and tear... etc
When that happens, we will end up with AC on our telephone cable. Our lines become the return path for the residential power. It can be dangerous, but normally we get reports of noise, loud hummmmm and such. So not to scare anyone, that return path is NOT the wires coming to your home, its the outer metal sheath of the telephone cable that is designed to normally shield your lines from outside interference.
You keep talking about a "dead short" at the receptacle. Is this the receptacle you are getting your power from? I am assuming this.
If so you will see a short from neutral to ground.
Is it safe to say that you didn't have a problem before you changed out the service?