[Samba] SAMBA 3.0 and AD Forrest - username is invalid

[James Trater]

I recently upgraded to SAMBA 3.0 on several Linux servers. My servers
are joined to a child domain that is part of a larger Active Directory
forest and I am using ADS security. Some of my users only have accounts
in the root Active Directory domain and other users have accounts in our
child domain. Since upgrading to SAMBA 3.0 only users with accounts in
the child domain can access their home directories via SAMBA (currently
the only thing being shared are the home directories). When users from
the top level domain try to access things, I get error messages in the
logs like: username TOPLEVEL.DOM\joeuser is invalid on this system .
This used to work perfectly with SAMBA 2.2.8. 

I need help! Thanks.