Mehdi: did you resolve your issue? I am getting the same problem as your #1 - being redirected to "Account/Login" instead of the WindowsSignin.aspx. However if I visit WindowsSignin.aspx directly it works for me (auto logs me in and doesn't pop up a login box, so the only problem is the auto-redirect isn't working.

1) When i disable Anonymous Authentication at website root level, i am not redirected to the login page nor do i get a login box, instead i am redirected to this url "Account/Login?ReturnUrl=%2f" with the "HTTP Error 401.2 - Unauthorized"
2) When i try to access "WindowsSignin.aspx" the page pops up a login box.

I have the same issue as listed Running on Windows Server 2008 R2, except when I navigate directly to this url
http://asktinto/DesktopModules/Authen...

Server Error in '/' Application.
Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272

If I open the root domain http://asktinto I get this in the url.
http://asktinto/Default.aspx?error=An...

the screen shows

This is with the App Pool in Classic, if I change it to Integrated, I get the following errors.

Server Error in '/' Application.
Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:
Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.]

DotNetNuke.Common.Utilities.XmlUtils.GetAttributeValue(XPathNavigator nav, String attributeName) +9 

DotNetNuke.Common.Utilities.Config.GetCustomErrorMode() +106 

DotNetNuke.Services.Exceptions.ErrorPage.ManageError(String status) +23 

DotNetNuke.Services.Exceptions.ErrorPage.OnLoad(EventArgs e) +309 

System.Web.UI.Control.LoadRecursive() +74 

System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2207 

I have this site working on a Windows Server 2008 SP2, the DB is SQL 2008 R2

and they are sharing the Same SQL DB.

I have followed the 3 resources
This Page
http://www.dnnsoftware.com/forums/for...
http://www.dnnsoftware.com/wiki/Page/...

I have compared both IIS Settings side by side ie 2008 SP2 and 2008 R2 and I am stuck...

I can run a clean DNN Site on 2008 R2.

Hope someone can shed some light...

Regards

Warren