I have a Windows XP computer on a Windows 2003 domain. This is a fresh install of vanilla XPP with Office 2007 and is fully patched. The computer joins the domain flawlessly over a VPN and the DNS on the VPN is set to the domain DNS server. Both the DNS server and the DC are hard coded in the hosts file. The problem is I get "The RPC server is unavailable" when I attempt to add any domain user to the local administrators group. Any thoughts?