samba - Mar 2008 - Urgent Help :How set "NT password" for an for an user

Hi All,

I have installed SAMBA 3.0.24 in my UNIX server. When I try to login
through an WINDOWS XP client, I found "NO NT password stored for user"
in the log, meant for my cleint name.

The log entry:-
[2008/03/07 15:51:32, 3] libsmb/ntlm_check.c:ntlm_password_check(189)
  ntlm_password_check: NO NT password stored for user grpuser.
[2008/03/07 15:51:32, 3] libsmb/ntlm_check.c:ntlm_password_check(356)
  ntlm_password_check: NEITHER LanMan nor NT password supplied for user grpuser
[2008/03/07 15:51:32, 3] smbd/sec_ctx.c:push_sec_ctx(208)

Then I checked in  ./pdbedit -L -v
It showing an entry w.r.t grpuser.

Can anybody help me out of this problem? It is an urgent thing I need to tackle.

Jay