It's not clear to me if you've just got the game and found this, or you've had the game running OK a while and now this has happened.
IF NEW:
Please go to C:\Program Files (x86)\Steam\steamapps\common\crusader kings ii\DX\ and run dxsetup.exe
Please go to C:\Program Files (x86)\Steam\steamapps\common\crusader kings ii\ and run vcredist.exe
If that doesn't help, please try installing ALL of these Microsoft modules:
First:
http://www.microsoft.com/download/en/details.aspx?id=8328
Then:
http://www.microsoft.com/en-us/download/details.aspx?id=35
(If that doesn't do anything then
http://www.microsoft.com/en-us/download/details.aspx?id=8109 )
Then: visit the Windows Update site and allow it to apply all .NET updates/patches it wants to, for all .NET versions.
IF OLD:
Please try a full
clean re-install:
- move any valued save games elsewhere
- "delete local content" in Steam-CK2
- manually delete all files and folders left under Steam/CK2 AND Documents/Paradox/CK2
- re-install game in Steam, run a Steam Verify when done.
IF NEITHER HELPS:
Please post a dxdiag.txt (you can delete everything after the end of the "Sound devices" section for brevity) and your Documents/CK2/settings.txt. From your Documents/Paradox/CK2/logs/ directory, post system.log . Open setup.log in notepad and search for 'checksum', post that line only here too please.