Hi Akshay

For point #1: Are you getting an IIS popup looking for credentials and the page the site is on is http://yourdomain/authenticationservices/activedirectory/windowssignin.aspx?..... ? If so then if you add the site to your intranet or trusted sites list in Internet Options then you should automatically login. What's happening here is happening before the majority of the login code is run for the AD provider. As for why Mozilla or Chrome only need the username I can't answer that. By default they don't like the IIS automated login and always ask for credentials. I know Firefox has a plugin for AD authentication so that it will pass the computer user crendentials through but the name escapes me at the moment.

For point #2: Sorry, you're going to have to live with that. While your site may be an intranet only site there are a fair number of users that run mixed mode sites (both internal and external users). If the username wasn't stored with the domain name appended first there's the possible chance of username collision (i.e. I'm on the DNN site as mikeh. If DNN corp every implemented the AD provider here and happened ot have an internal employee who had the username mikeh and he tried to login it would fail as his password would be incorrect. Actually I think it would disable my account because his account information would overwrite my information. The end result would be the same though (somebody wouldn't be able to login)).

Point #3: When you go to a manual login...Are you seeing both a DNN option and a Windows Login option? For domain users they have to click on Windows Login and then enter their credentials (if you have XXX as the default domain then they just need their username). If you don't have both options then check the settings for the AD provider and make sure that Hide Login Control isn't checked.