401 Errors

Improper NTFS Permissions May Result in IIS Failure
401 Access Denied error message in the HTTP response.
http://support.microsoft.com/?kbid=155253
List of NTFS Permissions Required for IIS Site to Work
HTTP Error 401.3 Unauthorized: Unauthorized due to ACL on resource.
http://support.microsoft.com/?kbid=187506
Access Denied for the Default Document File Mapped to Ssinc.dll
A 401 Access denied response is always sent to the browser (resulting in a password prompt) even if a valid username/password pair is entered.
http://support.microsoft.com/?kbid=246806
Error Message: HTTP 401.2 - Unauthorized: Logon Failed Due to Server Configuration with No Authentication
You are not authorized to view this page.
HTTP 401.2 - Unauthorized: Logon failed due to server configuration Internet Information Services.
http://support.microsoft.com/?kbid=253667
How to Troubleshoot 401.2 HTTP Errors with Reverse Proxy Web Publishing
http://support.microsoft.com/?kbid=261689
With WebShield Installed and Access Control Turned On, Proxy Server Clients Receive HTTP 401.1 or 401.2 Error Message
http://support.microsoft.com/?kbid=286409
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
NTLM Authentication Does Not Work If Internet Explorer Is Configured to Use HTTP 1.1 Through Proxy Connections
You are not authorized to view this page 401.1 Unauthorized logon failed
http://support.microsoft.com/?kbid=322822
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

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