Let me add - MacPro running Quadro 4000.
Close all applications (I mean all, including web browsers) and then start After Effects. Does After Effects start then?
Make sure that you have the most current drivers for you graphics card.
I did a complete reboot, and got this error:
Last log message was: <140735217804048><DynamicLink><5> /Library/Application Support/Adobe/Common/dynamiclink/7.0/dynamiclinkmanager.app