Win2003 Server Std. SP1 installed on Dell PowerEdge 1800 as Domain Controller, primary with no subforests. Can add Win2k and NT 4.0 clients w/o a problem. But when trying to add WinXP Pro SP2 clients, first logon takes over 3 minutes. Next symptom: For both W2k and WinXP clients, in Manage Computer, cannot add Domain Users to local Administrators group -- get "Processing of object Domain Users failed with the following error: the specified domain does not exist or could not be contacted." I've used the wizard to setup DNS but seem to feel that DNS is either misconfigured or the source of the problem. Am I on the right track?