Our TV really likes to turn itself on.  I just had to turn it off twice because it kept coming back on.  I used to think Kim was just leaving it on when she wasn't watching but I've seen it happen many times now when I'm by myself and nobody has been in the room.  It could be some sort of a glitch or maybe it was something the TV designers purposely included to tempt you into watching more television, but as always the safe bet is ghosts.