I have a more embarrassing one than that. Last week we were discussing here the switching of the auto-focus button to the button on the camera back, rather than using the shutter button. At that time I switched mine and thought I'd try it out.
A few days later I picked up the camera to shoot something and there was no auto-focus... completely dead! Checked that the lens was on AF, checked the seating between lens and camera, changed the batteries. Nothing. Just about to take it in for repair when I accidentally pressed the back button and it focussed!