Where did my ACL go?

I have a windows 2003 AD domain at home w/workstations running both 2000 & XP. If I want to set permissions on a folder on a 2000 machine, I have the option of either the local machine or domain. The XP machine only lists permissions for local users. I have tried re-joining this box to the domain and that didn’t work. Someone suggested that I have a DNS issue, but there is no problem for the 2000 machine. Any suggestions?