Unable to Log into Front PAge Server Extensions 2002 Administrator


I've noticed this question was asked, but there wasn't a satisfactory
answer. I have a Windows 2003 Standard Server that hosts several sites.
Each site is on the same IP and port, but they respond to different host
headers. Whenever I try to log into a web site (by going to
Properties->Server Extensions 2002->Settings), other than the default web
site, I cannot log in. I am presented with a password dialogue box, but
entering my server's administrative password doesn't work. Ultimately, I am
given the message:

HTTP Error 401.1 - Unauthorized: Access is denied due to invalid credentials.

When I initially extended the virtual server, I indicated my server's
administrative account should be the administrative account for the virtual
server. I've verified the ACLs on the directories and files, made sure my
web site had the same directory permissions, and a hundred other things.
Yet, I still can't log into the server.

Does someone know what the problem might be? I'm running out of ideas.