Schau dir das mal an:
Sollte die Lösung für dein Problem sein.
http://koti.mbnet.fi/akini/delphi/ntlmlogin/
Test NTLM login from application
This Delphi-demo application will make a login to NT Domain.
Username/Password/Domain is authenticated and success status is returned. If login was successful, then a list of NTgroups is populated.