Is it possible that the permissions for foxweb.dll are set such as the anonymous user (iusr_...) is not allowed to access it? I realize that this file is in the same folder as foxweb.exe, but it's possible that the file itself has different ACLs. Note that in some cases you need to restart IIS when you make a permissions change.
Also, make sure that you are not already logged into the server as a user that does not have rights to foxweb.dll. If you log in so that you can access a different resource, then you are no longer connecting as the anonymous user. The best approach is to set the permissions on foxweb.dll/exe, so that all users have access to them.
Sent by Valter Herman on 08/12/2008 12:26:24 PM:
The network security group at our company recently modified a server running foxweb 3.1 on Windows 2003 by removing the everyone group from some shares. This has caused a problem with accessing anything via the foxweb.dll (http://webserver/cgi-bin/foxweb.dll/show_cgi) ISAPI module.
When navigating to this URL the browser requests a username and password. No username and password works, all result in a re-prompt for a username and password. Clicking cancel displays the "HTTP Error 401.3 - Unauthorized: Access is denied due to an ACL set on the requested resource." error. Note this does not happen when accessing the same page via foxweb.exe (http://webserver/cgi-bin/foxweb.dll/show_cgi). Using foxweb.exe in the URL displays all pages correctly. Foxweb.exe and Foxweb.dll are in the same directory, the permissions are all the same and ISAPI is allowed for fwx files.