Most computer problems originate from PEBKAC.
My favorite is the lady who called in to complain that her coffee cup holder was broken. After a long go around trying to figure out how a computer could have a cup holder the tech finally discovered that she meant her CD tray. She had been jamming her styrofoam coffee cups into the hole in the tray and eventually it broke.
"Do not forget your dogs of war, your big guns, which are the most-to-be respected arguments of the rights of kings."
- Frederick the Great, King of Prussia