Recently a co-worker ran into an issue when working on a SharePoint demo environment. Whenever he tried to access the site settings page for a site collection he would receive an error page that stated “file not found”.
This made no sense since other web applications on the SharePoint demo farm were working without issues. After a bit of review it was discovered that he was using host headers for his web application but did not properly configure SharePoint’s alternate access mappings.
So morale of the story: Always double check to make sure you have setup your alternate access mappings for the domain names you are using with your SharePoint web applications.