Batman: Arkham City's control setup conflicts with one of my keyboard shortcuts. How do I fix this?

This conflict is often caused the keyboard shortcut for “Select the previous input source”, which can be the same as the in-game command for "Crouch" + "Use" (Ctrl + Space Bar).

To resolve this conflict, check your shortcuts against your control setup and disable the keyboard shortcut in question from inside System Preferences -> Keyboard -> Keyboard Shortcuts.