401 Error Message When You Use Application Center Test with NTLM Authentication
After you run a successful test in Application Center Test, you may not be able to view the test results, and you may receive the following error message during each attempt to do so:
401 - The requested resource requires user authentication http://support.microsoft.com/?kbid=322032
You Receive a "Page Cannot Be Displayed" Error Message When You Post to a Site That Requires Authentication
Internet Explorer may not post data from a POST request and you may receive a page cannot be displayed error message.
This problem may occur if the following conditions exist:
You perform the POST request on a new connection with a target page that requires authentication.
The server immediately replies to the POST request with a "401 Access Denied" response and closes the connection. http://support.microsoft.com/?kbid=821814