Primary DNS Suffix issues when joining domain

Not sure if anyone has experience with setting up windows 7 computers on a domain, but I'm running into an issue at work that I've decided to post on several forums in hope of a solution


This is an example of what I need to have set:
Domain name: a.b.buffalo.edu
Primary DNS suffix: c.buffalo.edu



The problem is joining the domain results in:

"Changing the Primary Domain DNS name of this computer to "c.buffalo.edu" failed. The name will remain "a.b.buffalo.edu".

So it remains computer.a.b.buffalo.edu instead of computer.c.buffalo.edu. I then need to specify the correct DNS suffix, enter my domain credentials, and reboot again.



I have tried setting the Primary DNS Suffix through group policy for the OU and by modifying the registry entry for the primary DNS suffix but both of these methods result in the following error at logon:

"The security database on the server does not have a computer account for this workstation trust relationship"