RDC connection from Mac to Server 2008 R2 fails for some users but not others with "The remote computer is not allowing connections from the Mac"

I'm having problems connecting from Macs to Windows Server 2008 R2 servers. The Macs are running RDC 2.1.1 on 10.6.8.

I can connect fine in these circumstances:

connect to FQDN using DOMAIN\Administrator

connect to IP using DOMAIN\Administrator

connect to IP using DOMAIN\<user> (who is also a member of Domain Admins)



However, if I connect to FQDN using DOMAIN\<user> I receive the error message "The remote computer is not allowing connections from the Mac" and the server records a 4624 event with

New Logon:

Security ID: ANONYMOUS LOGON

Account Name: <user>.


When I use the IP address, I get in and the server records a 4624 event with

New Logon:

Security ID: DOMAIN\<user>

Account Name: <user>.

And if I use DOMAIN\Administrator, I get in with either the FQDN or the IP.



Other notes:

I've tried with the Macs as members of domain and I've taken them out of the domain and see the same behavior either way.

<user> is a member of the groups Remote Desktop Users and Domain Admins and also has been granted remote access individually.

Allow connections from computers running any version of Remote Desktop (less secure) is enabled.