We setup a domain controller (Global Catalog) a the parent domain and added several subdomains for testing and learning. The problem is the users accounts in the parent domain cannot log onto the subdomain machines. All of the user are part of the domain admins group and when we try loggin onto the parent domain from the subdomain machines it complains that the machine is not trusted. I am wondering if adding the subdomains as GCs and with the DNS option has anything to do with it Steven Kirwin

I believe this is by design. A domain joined computer in an OU with default GPOs will allow DOMAIN\Users to log on, but to allow users from other domains you will have to grant DOMAIN2\Users the Allow log on locally right. (This is taken from memory I have to admit, but it should give a clue.)

The problem is the users accounts in the parent domain cannot log onto the subdomain machines. One of two things here. 1) You are not specifying the correct login domain. This can be done by clicking the Options button, or by typing domain\username in the login box 2) The DomainX\Domain Users group or Authenticated Users group must be a member of the workstations local Users. If you are still having issues post the Exact error, and more information about your domain structure. All of the user are part of the domain admins group and when we try loggin onto the parent domain from the subdomain machines it complains that the machine is not trusted. What??? You have skipped providing some important details. Like the name of the the domains and the forest structure, and which domain these users are in? What is your forsest root domain? What are the child domains and what are the sister domains? What domains are the workstations a member of? Which Domain are the users a member of the Domain Admins groups? What is the exact error message?