IIS 5.1 problems with a specific user

[Max Power]

Hello-

I am having a bit of a problem with a specific user trying to log on to an FTP server I have set up using IIS 5.1. I apologize if the following has been discussed before; it's such a weird problem that I don't know exactly how I would go about wording a search for it.

On my FTP server, I have turned off anonymous log-ins, yet whenever this specific user tries to access the server on 3 different Windows 2000 SP4 machines, he is pushed through as anonymous and can't see anything. He is using IE 6.0 to access the server with all critical updates installed. If I try logging in as the user on my machine, running Windows XP SP2 and the most current version of IE, I am able to successfully log-in as him and see the virtual directory I have set up for him. All user accounts described here are Active Directory accounts, unless otherwise stated. Users are logging in as domain\username.

What's really strange is another user, who has the same permissions and whose virtual directory is pointing to the same location, can log-in with no problems on her Windows 2000 SP4 machine, AND can log-in to the FTP server on the supposed problematic machine while still logged in to our domain as the problematic user! I have tried every setting I can think of, clearing the Temp. Internet Files, clearing the AutoComplete, restoring web settings and resetting the defaults, and nothing seems to work, everything short of reinstalling IE (as best as one can). I have even gone as far as creating a local user account on the FTP server for the user and I still get the same result. Does anyone know what may be going on here? Could this be a buggy AD account?

The FTP server itself is pointing to a specific home directory on a D drive (250gb hard drive). I have set up 7 virtual directories pointing to locations on the C drive to act as a test for 5 users before setting them up on their own FTP server. All permissions are the same for each user, and I am only having this problem with the one.

Any help you knowledgable folks could offer would certainly be much appreciated. Thank you!