You might want to read this.

http://blogs.msdn.com/sql_protocols/archive/2006/08/10/694657.aspx

If you have access to AD console.msc to view some of the setup, you should be able to start reviewing the computers and accounts involved.

Setspn ( a tool in the resource kit for W2000 server ) can be used to look at the endpoints that are setup.

Since Domain Admin is required for much of the setup, you might just want to get one involved early in the process. They should be helpful in resolving this.

Greg E