Symptom: Game will not run and stops with an error that starts off with ‘Localized Resource’ even if you uninstall and reinstall the game.
Possible Cause: Downgrading from windows 10 to windows 7 after installing CoD UO may cause an issue that is persistent even if you uninstall/reinstall the game. Unlike Windows 7, Windows 10 stores large amounts of cache to make the system faster and more responsive compared to previous versions.
Solution: If you went back to windows 7 you need to check for a ‘cache’ files that were written by Windows 10. These file(s) need to be removed before you can run the game in Windows 7. The file was called ‘System.cache’.
*Note – To get to the hidden folder quickly, open the run command and type or copy and paste “%LOCALAPPDATA%\VirtualStore\Program Files (x86)” and press enter.
You will see a folder named the same as the CoD install folder was named like ‘Call of Duty’. Look inside of this folder for any system cache files and remove them. (Must have hidden files shown to see them. Press the Windows key and type folder options and make the change as shown)
Best practice to downgrade from windows 10 to Windows 7 would be to do a complete system cleanup before performing a roll-back or win10 uninstall, or better yet, do a clean install of Windows 7 entirely to avoid this and a few other issues I have heard of.