This is known issue with SharePoint 2007 or SharePoint 2010 on Windows Server 2008 platform and not specific to any sharepoint application. Problem: Your windows credential doesn’t work if you try to log in to the web application (http://contosto.company.com) on the server itself although you can access the same site from outside, when you create a SharePoint web application with a host header (contosto.company.com) on SharePoint Server (Server Name: contosto) which is installed on Windows Server...