Roll back to NT 4

Here is the scoop. My boss wanted us to migrate to Windows 2000. A consultant was here doing the migrating. He is not here anymore and niether is my boss. My new boss says lets go back to NT 4 because we are have little problems show up all the time. We have a Windows 2000 domain controller (Active Directory) with other NT 4 domain controllers. (Mixed mode)

Question. How can I go back to a NT 4 domain safely?

Need more info? Let me know