I have upgraded from 12.04 to 14.04 on my laptop. The upgrade was successful, but the issue is that nothing happens now when I click on "LogOut", "Shutdown", "Suspend" from the top right power icon (not sure if this is the proper name); "Systems Settings", on the other hand works and launchs the associated window. Not a big issue, though, since I can logout and shutdown from a terminal, but I'd like to know why is this not working and how can it be fixed. Any ideas on how to solve this?