I've just installed 4.0.1 yesterday, and now I'm trying to learn how to configure the system to use Active Directory authentication. I have setup the Authentication module talking to Active Directory (green light), and I've configured the /Admin/Security/WindowsSignIn.aspx page to require authentication.

1) So how does the user login? When I go to the login page it doesn't authenticate me to the active directory.

2) Once I have Active Directory authentication working, is it possible to use a mixed mode authentication (DNN & AD) at the same time?

3) Are user roles required to be bound in AD or to DNN? In other words, where do I have to set up permissions?

Yes you can and it's been answered in a number of posts before. If you comment out <add name="Authentication".... /> under <httpModules> in your web.config then you can run in mixed mode. However your AD users will no longer be logged in automatically and will have to manually enter their user credentials (DOMAIN\Username). With the next release of the provider (which is currently in the Project Release Tracker) there is an option to specify IP ranges for auto-login which will hopefully allow AD accounts to auto-login and DNN accounts to manually login (it's working great in all of my test environments so far).

I'm afraid I need more detail on where you're seeing this problem. Do you mean when you're trying to assign roles or just add a user manually?