Please do a full **clean** re-install:
- move any valued save games elsewhere
- "uninstall" in Steam-CK2
- manually delete both the Steam/SteamApps/common/CK2 AND Documents/Paradox/CK2 folders
- re-install game in Steam, run a Steam Verify when done.
- add ck2game.exe to the exceptions list/whitelist of your antivirus app
- start the game with no mods active and test
In particular make sure there are no files or folders left under either the Steam CK2 or Documents CK2 locations, before installing again.
Also if you have installed a gaming VPN app called Evolve, or the MSI Gaming App, or Duet, disable it as it clashes with this game.
IF that doesn't help, DXDIAG is a program you run from a command prompt or the Windows start menu 'run' dialog box (or 'search programs' in Windows 7 or later). After running it will open a window and start collecting info with a progress bar in the lower-left corner. When it completes click the 'save all information' button and save it to a file then attach that file here.
Please attach your Documents/Paradox/CK2/settings.txt.
From your Documents/Paradox/CK2/logs/ folder, attach system.log .
