[KLUG Members] Squid users cannot login to a Win2003 IIS server?

[Bruce Smith]

We just started to have a problem when trying to log into a remote
Win2003 IIS web server while going though a squid proxy server.

Without squid, the site pops up the login user/password box fine.  When
the proxy settings are set to use squid, we never get the login box, and
this page appears in the browser window:

======================================================================
You are not authorized to view this page
You do not have permission to view this directory or page using the
credentials that you supplied because your Web browser is sending a
WWW-Authenticate header field that the Web server is not configured to
accept. 
________________________________________________________________________

Please try the following:

      * Contact the Web site administrator if you believe you should be
        able to view this directory or page.
      * Click the Refresh button to try again with different
        credentials.
HTTP Error 401.2 - Unauthorized: Access is denied due to server
configuration.
Internet Information Services (IIS)

________________________________________________________________________

Technical Information (for support personnel)

      * Go to Microsoft Product Support Services and perform a title
        search for the words HTTP and 401.
      * Open IIS Help, which is accessible in IIS Manager (inetmgr), and
        search for topics titled About Security, Authentication, and
        About Custom Error Messages.
========================================================================

The login userid is very domain'ish (contains a backslash: xxx\xxxxxxx).
I've even had the web server admin turn on basic authentication in IIS.
So far nothing has worked.

Any clues?  I've been searching and haven't turned up a solution.

 - BS