I set security settings of Hudson as shown in the attached image.
Under the settings, I can access http://<hudson_root_url>/ (i.e. http://127.0.0.1:8080/)
correctly when I use Firefox 3.6.12 and Google Chrome 8.0.552.224.
However, I can't access the root URL when I use IE8 (8.0.6001.18702).
In this case, IE8 returned the status 403.