I've read all the postings here for help and all of the microsoft KBs and other forums. My situation is I have a 2000 Domain and a new 2003 domain. Different forests each running it's own DNS. Both Domains are on the same network. I have setup the dns forward lookup zones on each and verified each is working according to other posts here. What I have a problem with is when I disable the windows firewall on the 2003 server everything works fine, no problems and fast, when I turn the firewall on, the trust disconnects and I get RPC server unavailable errors. I have setup exceptions in the firewall according to MS recommendations and other suggestions from here. None work. Has anyone found the "magic" ports to open? I would prefer to leave the firewall on.