Outlook 2007 no longer able to connect to Exchange 2000 server

I have one desktop out of 20 that all of a sudden cannot connect to
the exchange server. This workstation happens to have our main
shipping software installed that has a bunch of ODBC connections
configured so it will be a REAL pain to 'wipe and start over'.
What happens is this.
When you try and check the configuration it says the 'name cannot be
resolved' when entering the Microsoft Exchange Server. This happens
whether I use the FQDNS name, the NetBIOS name, or the IP address.
The thing that stands out most for me about this problem is that the
error is instant. You click on the "Check Names" button - the error is
straight up - no delay. It is as if it isn't even trying to connect to
the server, the same sort of behaviour I would expect if there was a
firewall blocking it or something.
This is the only machine having this issue.
Things I've checked or tried.
No software firewalls installed.
Windows firewall disabled.
Cached, non-cached mode, doesn't matter.
Remove exchange and add the correct type of account.
Remove/rename .ost file(s)
The user account is valid. I am able to have that person log into
another machine and create an Outlook profile that works.
We can connect via Outlook Web Access on this machine to the account
and send and receive mail!
There are no other network issues with this machine - that I can tell.
All other network shares, connections and applications work.
I can browse to the exchange server via name in windows explorer on
said machine.
I can browser via IE and fire fox via name to mail server on said
machine.
I have put the exchange server name in both host file and in lmhost
file and vice versa and removed/switched etc.
I have re-installed the NIC drivers.
I have added the RPC DefConnectOpts key etc.

Any help would be greatly appreciated. Dying here.
I am ready with a big hammer.
Thanks