Administrator can't access network resources from XP

Hello all:

Hope someone out there can help me out. Here's what I
have:

Client = Windows XP (all service packs and patches
applied)
Server = Windows 2000 Adv. (all service packs and patches
applied)

When I logon to the domain as administrator I get
validated to the network. When I try to access resources
on the domain controller I get an access denied error.

All permissions are set properly. Local administrator
group ahs full control. When I add the everyone group,
permission is granted.

It seems like I am not getting properly authenticated to
the domain.

Oh yeah, when I access the same resources through my
Windows 2000 Member server, there is no problem. I am
logged on with the same account.

Any help would be great.

Thanks

Peter