You must be a member of the Domain Admins, Schema Admins, and Enterprise Admins groups
Windows Small Business Server 2003 Setup cannot continue because the account you are logged on with does not have permissions to access the schema. During Setup, the schema is updated and Active Directory objects are created. This requires you to be a member of the Domain Admins, Schema Admins, and Enterprise Admins groups.
You must cancel Setup, log on using an account that is a member of all the specified groups, and then restart Setup.
If you add your account as a member of any group, you must wait for the changes to take effect in Active Directory. If you restart the server, the changes will update immediately. For more information about adding a member to a group, see Help.