You may experience authentication issues browsing http://companyweb on SBS 2003 and SBS 2008 servers after installing the cumulative security update for Internet Explorer (963027) or Internet Explorer 8.0.  When you try to browse Companyweb you will be prompted for authentication 3 times and eventually receive a blank page or 401.1.  Your IIS logs will show your request failing with 401.1 Unauthorized. Resolution: On an SBS 2003 server, apply update KB961143. And SBS2008 refer to this post, or KB963027

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