In the system tray, right click the "Norton Internet Security" icon and select "Open Norton Protection Center".
In the main window, go to "Options" and select "Norton Internet Security".
Inside the "Norton Internet Security Options" window, go to "Program Control" where we must click the "Add" button. Search for the file RegnumOnline.exe located at "C:\Program Files\NGD Studios\Regnum Online" and accept.
After that, a new window will open (like the one pictured below) in which we will select "Allow" and then OK.
Repeat the same procedure for the file: ROClientGame.exe located at "C:\Program Files\NGD Studios\Regnum Online\LiveServer"