Hi,

I will not take the credit for the solution, but if you want you F11 Key work normally on a Mac (usefull when you install ESXi or remote console on server)….

In Settings, Mission Control, UnBind the F11 / F12 Key to nothing

Source : http://apple.stackexchange.com/questions/110525/how-do-i-get-f11-and-f12-to-behave-like-normal-function-keys