DCOM problem with Win2000 vs Win NT


I have a DCOM-based client/server app which was working fine on a Win2000
system: Both server and clients running on Win 2000 Pro machines (with fixed
IP addresses - if this means anything?).

Problem: The system is migrated to NT: the server on Win NT Server and the
clients to Win NT Workstation SP6 (DHCP server on this system). With the
server on a NT machine and a client on my W2K-machine, it works, but the
NT-based clients cannot connect to the server. It runs up to this line:
  HRESULT hr = CoExams::CreateRemote(WideString(m_Server),&m_ExamsServer);

  m_ExamsServer = CoExams::CreateRemote(WideString(m_Server));
and never returns from the CreateRemote function...

Any suggestions?