Unzooming a Really Really Zoomed in Mac Screen

Matt and I had a user accidentally magnify her screen big time tonight (the Firefox icon in the dock took up the entire screen). For some reason "Command + Scroll" was not working even with a separate mouse. She had been writing a paper and asked if we could not restart the computer if possible. We found the easiest way to get her screen back to normal was to go into system preferences (which was fun with the screen completely zoomed in) and go to Mouse Preferences and uncheck the option "Zoom using scroll ball while holding:" option. It is at the bottom of the menu. Hope this helps some people with future problems!