domain admins/ proxy server

2 weeks ago I installed the update for nav and also the iislockdown tool 2.x
The result is that on a nt proxy server only members of the domain admin groups can connect via the proxy server. Normal domain users get the default dns error page in IE.

When opening outllok express they get the following error.
The host ‘pop3.interneeds.net’ could not be found. Please verify that you have entered the server name correctly. Account: ‘pop3……….’, Server: ‘pop3……….
‘, Protocol: POP3, Port: 110, Secure(SSL): No, Socket Error: 10050, Error Number: 0x800CCC0D

Sometimes they get an error that the port 110 is already in use.
However if they are in the domain admin group they can connect fine and they don’t receive those errors.
Leopold