I'm trying to post it again... Goes like this: Believe it or not this problem is still active! I've tried all you guys wrote about setting DNN for AD support, downloaded latest DNN installation (05.04.01) and things happened like this: 1. Forms authentication - AD user logged in by forms authentication is created in DNN and logged in. 2. Windows authentication - AD user previously logged with form authentication also successfully logged in. 3. Windows authentication - AD user that I just created and never been logged in with forms authentication makes endless loop page error we all seen. Since I've been testing this for 3 days trying to figure out what is this all about and have passed all problems you had I decided to put up another DNN project and did't installed AD provider. I switched to windows authentication and received loop page immediately. I mean there is no clear explanation how AD provider should work. I saw it create user in DNN when logging with forms auth. and I guess it should do same thing under windows auth. IS THAT TRUE? What is purpose of windowssignin.aspx page? Everyone talk about redirecting to it but no one tells why! In best moment I reached every page just like windowssignin.aspx asks me for windows username/pass and keep looping. I downloaded third party demo module for DDN called Easy AD and its easy to install and implement but I have same problem. Switching to windows authentication I keep getting endless redirection. Should I read remaining 99% of web since I red pretty big 1%? I think I'm mistaking somewhere but I cannot see where.... I really hope that there will be some explanation for this problem since as I see everyone stucked on it and never implemented AD and windows auth. Lucky bastards managed it to work probably forgot about rest of us enjoying their solution:) Thanks a lot!