When you go to your DNN website, and click the login button, you are taken to a page that does not have a logon module on it, so you are not able to log in or you get the following errors:

The page isn't redirecting properly

Firefox has detected that the server is redirecting the request for this address in a way that will never complete.

    *   This problem can sometimes be caused by disabling or refusing to accept
          cookies.

You have changed the Login page for your DotNetNuke website.  You will need to reset it.

1)  Go to this url:
http://YourDomainName.com/Admin/SecurityRoles/tabid/41/ctl/Login/Default.aspx
(replace YourDomainName.com with your domain name)

2)  Log in as your host dnn user.
3)  Add a new page to your DNN site.  Use these parameters:
Page Name:  Login
Include In Menu: No (Unchecked)
All Users have VIEW permissions.
4)  Add a login module to the page.
5)  Go To Admin > Site Settings and set the Login Page to the Login page you created.