client turned my macpro tower into an extended desktop?

opened the client and firefox was tossed onto an extension of my desktop that wasn't there. i lost my ability to remove ifirefox from fullscreen when on it and can only return via hitting the dashboard hotkey in order to get back to league if i use my dock to go to firefox. i do not understand this and have never experienced anything like it before. i can not even minimize firefox to get out of this issue. only option to get back to my actual desktop and have my "dock" strange behaviour. osx 10.7.5 4gb ram Graphics ATI Radeon HD 5870 1024 MB

(Edit for added into) force quiting firefox made the issue of extended desktop go away(although the extended desktop was not like a normal extended desktop in the fact i could not mouse over to it, only use the dock to select program or dashboard hotkey to swap over pages)