Have you tried to use Steam to verify integrity of game cache?
If so, try the following:
Make sure to backup any potential save games you would like to save first.
-Remove your Crusader Kings II folder at "My Documents\Paradox Interactive\Crusader Kings II"
-Do a clean re-install of Crusader Kings II
-When starting the game, make sure you don't have any mods active
If so, try the following:
Make sure to backup any potential save games you would like to save first.
-Remove your Crusader Kings II folder at "My Documents\Paradox Interactive\Crusader Kings II"
-Do a clean re-install of Crusader Kings II
-When starting the game, make sure you don't have any mods active