I use Ubuntu 12.04 with Unity 2D and I've stumbled upon this issue: sometimes shortcut keys stop working in some windows. For instance, I have these windows opened usually: Google Chrome, Terminal, Skype, Pidgin. Sometimes everything is OK and shortcuts work no matter what window I hit them from, however, hotkeys hit from Skype (more often) or Pidgin (less often) do not work, but they still work from Terminal or Google Chrome. Moreover, not all hotkeys are affected, the problem holds only for locking the computer (Ctrl + Alt + L) and other custom shortcuts like executing some command or launching a program (I used zenity --entry with [Super | Ctrl] + [some letter: K, N, etc] for testing). Does anyone have a clue what is causing the problem and how to fix it?