401.3 error

I set a folder on my public web (sitting on the DMZ), using NT challenge response.
Everytime I access it from my trusted network I get ”
401.3 Unauthorized: Unauthorized due to ACL on resource ” with netscape, IE displays ” The page you are looking for is currently unavailable….”

But if I access the same folder with same usr/pass from the web or as a VPN user, I have no problem. Of course, when I allow anonymous access, I have no problem.

I use a user member of Domain Users group andit’s a global account.