Error loggin to Domain

When I connect to a windows 2000 domain with XP, I connect ifne the first time and it copies my profile to the server when I log off. But when I logon the second time I get the following message.
Windows cannot locate the server copy of your roaming profile and is attempting to log you on with your local profile. Changes to the profile will not be copied to the server when you logoff. Possible causes of this error include network problems or insufficient security rights. If this problem persists, contact your network administrator.

DETAIL – The system detected a possible attempt to compromise security. Please ensure that you can contact the server that authenticated you.

Any suggestions?