Creation of postgres user to cygwin.

I tried to install postgreSQL to service as mentioned in the
postgresql-7.2.README document.
When I try to login to postgreSQL as a postgres-user I am however getting
following error:

      login: postgres
      Password:
      Fanfare!!!
      You are successfully logged in to this server!!!
      login: no shell: /bin/bash: Permission denied

      Administrator@NERIAH ~
      $

I am running Windows 2000 as a user belonging to my companys NT-Domain. The
postgres user which I created to Windows, is local user.
If I logon to Windows as a local postgres-user, then I can also logon to
Cygwin as a postgres-user.
(Then I will get again same error-message if I try to logon as a
Administrator-user)

I tried to read documentation from ntsec in
      http://cygwin.com/cygwin-ug-net/ntsec.html
but I really did not catch up what I should do...

Mika