2 months ago - AndrewT - Direct link
When you say "slowdowns in games", which games aside from this one are you referring to?

Right click on eu4.exe , properties, compatibility. Tick "disable fullScreen optimisations" untick every other box in that dialog, Apply and exit.

Edit that settings.txt to say:



Then in the launcher Game Settings menu, select fullScreen display mode.

IF that doesn't help:
DXDIAG is a program you run from the Windows search box on the task bar. 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 here your Documents/Paradox Interactive/Europa Universalis IV/settings.txt and pdx_settings.txt .
From your Documents/Paradox Interactive/Europa Universalis IV/logs/ folder, attach here system.log , error.log .  
2 months ago - AndrewT - Direct link
What do you see if you run eu4.exe directly from File Explorer? Any Windows error show?  
2 months ago - AndrewT - Direct link
You haven't set eu4.exe to run as the Admin user, have you?

Aside from that, I don't know why the launcher will not start the game any more.  
2 months ago - AndrewT - Direct link
Sorry, I'm not quiet clear - if you have set eu4.exe to run as Admin, undo that please.

Otherwise do a full **clean** re-install:

- move any valued save games elsewhere
- "uninstall" in Steam-EU4
- manually delete both the Steam/SteamApps/common/Europa Universalis IV AND Documents/Paradox Interactive/Europa Universalis IV folders - In particular make sure there are no files or folders left under either the Steam EU4 or Documents EU4 locations, before installing again.
- re-install game in Steam, run a Steam Verify when done.
- add EU4.exe to the exceptions list of your antivirus app; ESPECIALLY if you have Windows Defender, add it to the Ransomware "Apps Allowed Through" list.
- start the game with no mods active and test
- if still a problem, implement the settings from post #2 aboev again

Good luck!