Most likely it is a registry problem.
Here is a link to instructions on manually uninstalling Victoria, including the registry entries, the procedure will be basically the same for CK so it should sort you out.
http://www.europa-universalis.com/forum/showthread.php?threadid=114642
Here is a link to instructions on manually uninstalling Victoria, including the registry entries, the procedure will be basically the same for CK so it should sort you out.
http://www.europa-universalis.com/forum/showthread.php?threadid=114642