Hello Smigen,
The checksums validate if the game is correctly installed, is modified etc. Also after you've started a game, you will notice that when you go back to the menu that your checksum has changed, fully restarting your game will bring you back to the correct checksum.
The correct checksum for the 1.103 patch is WQLL, so there's something wrong with your installation or you've modified the game files. Have you already tried to verify the integrity of the game cache?
- Open your Steam games library
- Right click on "Crusader Kings II" and select "properties"
- Click on the tab "Local Files"
- Now click on "Verify integrity of game cache"
- Wait until this process is finished, if any files are missing/corrupted it will notify you at the end of the process and automatically start with redownloading these files
If that did not help, then do a
full clean re-install of the game.
- Important:: Go to '..\Documents\Paradox Interactive\Crusader Kings II\save games\' and copy all the save games you want to keep outside the folder
- Uninstall Crusader Kings II
For Steam users: uninstall the game from within steam by right clicking on the game and select "Delete content".
- Go to the folder where you installed Crusader Kings II in, and check if the Crusader Kings II folder is removed. If not, delete the entire folder
For Steam users: Installation folder can be found at: '..\Steam\SteamApps\common\'
- Go to '..\Documents\Paradox Interactive\' and remove the entire Crusader Kings II folder
- Reinstall the game, make sure you install the game outside the 'C:\Program Files\' or 'C:\Program Files (x86)\' folders, as it can cause issues with permissions