There is an outlet in the attic just above the living room that the multiswitch is plugged into. This outlet is on the same line as the switch, and it gets the power cut off every time I switch off the light.
Sorry for your troubles, but this is too funny.
In a somewhat related story, I was visiting a friend of mine once and he told me that his garage door opener stopped working and he was about to go and spend about $120 on a new one. So I decided to take a look at it for him to see if I could save him a little bit of cash. The first thing I did was unplug the opener and test the outlet with a multimeter. Of course, the outlet had no power, so I told him to turn off the circuit breaker then turn it back on. Still no power. I then noticed a light switch on one of the walls in the garage and asked him what it went to. He said that it didn't go to anything that he knew of, so I told him to turn it on. The power came on. I'll never let him forget about that one.
The funniest thing to me is that he had been living in the house for about 8 years and never knew what that switch operated.