Small Business Server Domains

I'm setting a Small Business Server system. Right now I'm just doing testing and have a single Windows XP Pro client. I went into the system and created a user and added the computer to the domain (using the built-in wizard that runs at setup time). I'm then directed to go the client system and point the browser (IE 6 in this case) at a URL on the server. I can get to the server just fine (pings also work between the systems) but, when I try to join the client to the doman, I get a message indicating that the list of computers in the domain can't be found! When I go into the Active Directory on the server I can see that both the username and the client computer are present. Anyone ever seen this and/or know of a solution?

Thanks.