Please try a full clean re-install:
- move any valued save games elsewhere
- "delete local content" in Steam-EU4
- opt into the 1.8-hotfix beta in the Steam EU4 beta tab
- manually delete all files and folders left under Steam/EU4 AND Documents/Paradox/EU4
- re-install game in Steam, run a Steam Verify when done.
If that doesn't help, Please post a dxdiag.txt (you can delete everything after the end of the "Sound devices" section for brevity) and your Documents/EU4/settings.txt. From your Documents/Paradox/EU4/logs/ directory, post system.log . Open setup.log in notepad and search for 'checksum', post that line only here too please.