Internet Exploder's default error page is "Cannot find server or DNS error" rather than the old "unfriendly" 404 (can not find page) or 403 (Forbidden / permission denied). In much the same light, many web servers have started not returning 404's in favor of always returning 403's (makes it a bit tougher to find "hidden" pages (ie. where you don't have the proper credentials) this way).