re: Electrical help

It kind of sounds like somebody added a switch to an existing light circuit by just dropping 1 wire down to a switch and tying in the switch to the box in the ceiling. Does it look like the switch was added after the house was built? I would take off the wall plate and check the switch. Correct installation would have the whites wire nutted together and the blacks on either side of the switch. If there is only 1 white and 1 black in the switch and they are connected to either side of the switch than what I am saying is true.

In that case one of the whites in the ceiling box is acting as your switched hot. Its definitely not how it should be done but I've seen some crazy things. I would use a voltage tester to verify.