I upgraded from 15.04 to 15.10 to about 15 days ago. Now i started facing a problem which appeared about 3-5 days ago. I am not able to shutdown my laptop from the desktop, when I click on shutdown from top-right gear icon on desktop, I just logged out but I am able to shutdown from there and also from terminal.
I also checked: I can't shut down nor reboot without console but it did not help.
Hope it helps. Thank You P.S.-Sometimes my laptop shutdown from left-hand gear icon(as it happened today sometimes).