A weird bug I came across: Clicking on a folder within your dock (like Downloads) will turn hiding on for the dock, even if it was turned off the second before. This is after a fresh install of Mountain Lion for a 2008 Mac Pro. It's very confusing for my father. Weirdly enough, this issue isn't affecting anyone else in my family (my MacBook Retina and my mother's 2009 13" MacBook Pro). Does anyone have any suggestions? Is there an option I've accidentally enabled?