Your NT username and ID are your Windows login name and password. What sites are asking for this information? They should only be asked for when you Turn on your PC, Reboot your PC, login to a proxy, login to a corporate domain, or VPN. You may have a trojan attempting to get your login info. Let me know what sites are asking, please.
I have new Comcast internet service. When I logon to other email accounts or financial accounts I get a popup saying sign in NT User Id and password. I have called tech help 4 times and they say the only user name and password they know is for logging to their website. That doesn't work.