I just updated Ubuntu 16 LTS and after the restart I can't use Ctrl Keyboard combinations (Ctrl + C, Ctrl + Right, Ctrl + T ...) in applications anymore (neither left - Ctrl nor right - Ctrl). I'm using a Gnome-3 desktop and here Ctrl seems to work, e.g. in search I can Ctrl + A and the System-Keyboard-Application recognizes left/right - Ctrl presses. It's only in all User-Applications and the terminal that I can't use Ctrl. All other shortcuts seem to work fine, even Ctrl + Mouse-Scroll to zoom.
I have no custom shortcuts.
I wouldn't be sure it has anything to do with the latest update since I also installed a lot of applications since the last restart.