I like misson control (aka Exposé) in Mac OSX and the spaces functionality, which allows you to control multiple desktops in Mac OSX. Sincce 10.8.3 I noticed sometimes that the spaces just won't show up anymore in Misson Control. To me it seems to be a problem with the Dock as well. The Dock doesn't display correctly. So open up a terminal and enter
after that your spaces within Mission Control will be back and the Dock will restart.