
Originally Posted by
cPanelDavidG
The HTTP Authentication window (what you call "Windows login pop-up") should be authenticating users, avoiding the need to view any login screen.
However, if you wish to not use HTTP authentication in favor of the lesser secure Cookie-based authentication, you can change that via WHM -> Server Configuration -> Tweak Settings -> System and check the setting for Disable Http Authentication for cPanel/WebMail/WHM Logins (forces cookie authentication) - be sure to click save at the bottom of that page.