I've seen this condition quit a few times in these older houses. Whoever wired the house in the beginning probably ran a home run to a light fixture and branched off with several (read 5 or 6) more runs to outlets throughout the house.

The problem is more than likely up in the living room ceiling fixture where they thought they were wiring up the light and got a neutral on a hot!

Seen it happen a bunch were somebody tries to save a wire and uses the black for the hot going to the switch with the white also tied into the switch to run back to the light.