The responses have been that you either have 1) an unbalanced load or 2) a loose neutral connection.

So here's my question(s).
1) Re: unbalanced load. Let's say that the only electric usage in the house is a couple of table lamps on one branch circuit and the
furnace blower (gas furnace so only current draw is the blower) comes on. Won't this ALWAYS create an unbalanced load? The
starting draw for the furnace blower is going to be WAY more than the two lamps. I guess I don't understand what is meant by
"unbalanced load". What is is and how can I check for it and what is the solution????

2) Re: loose neutral connection. Given the table lamps and furnace blower scenario, would I be looking for loose neutral
connections only on those two circuits and only where current is being used? Meaning, loose connections at the two lamp outlets
or where this circuit attaches to the neutral bar at the panel or at the neutral connection to the furnace blower or where that circuit
connects to the neutral bar at the panel or the MAIN neutral connection. That is to say, it wouldn't do any good to go check the
neutral connection for the bathroom light in this example, right?

Bottom line, can anyone give more troubleshooting hints than "unbalanced load or loose neutral"??