Do you have a PS3 remote? They made a horrible decision in making it turn your PS3 on by the press of any button. My cats used to step on it and turn the system on until I started keeping it under the chair or couch.
I used to have a cat I would blamed for running in back of my tv and turning off the power strip back there. Supprisingly it turned out a rat was in the house doing that and not the cat. Got rid of that rat fast.