Thanks a bunch for the help @sawest !!!

This is the first error received in testing. I am testing the login with an email address "[email protected]" and receive the following error. Remember now the user "joebags" is a valid user. The domain "donutzrus.com" is NOT our AD domain. So in reality this should return a regular error message for login failure.

Message:Object reference not set to an instance of an object.
StackTrace:
InnerMessage:Object reference not set to an instance of an object.
InnerStackTrace:
at DotNetNuke.Authentication.ActiveDirectory.ADSI.Utilities.UPNToLogonName0(String UserPrincipalName)
at DotNetNuke.Authentication.ActiveDirectory.Login.get_UserName()
at DotNetNuke.Authentication.ActiveDirectory.Login.cmdLogin_Click(Object sender, EventArgs e)
at System.Web.UI.WebControls.LinkButton.OnClick(EventArgs e)
at System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)