Exchange 2007 Wizard not seeing domain users

I was trying to create a spam quarantine mailbox and add it to an existing user - and also reconnect a disconnected mailbox through the Exchange System Manager, and the wizard does not display (ANY) of the domain / AD users other than the default Quickbooks accounts created locally. I have tried changing the scope, searching, etc.

Also - I noticed that previously I was able to view MS Exchange tabs in active directory, and now they are gone.

Any help would be much appreciated.

Thanks,
Robert