samba - Aug 2007 - Security share and problem with unix groups login.

I've expirienced strange problem with unix group login in samba recently.
This is
unusuall because users given in "username" pramater in share can log
into it, but if I
add group of users that group cant log in to share. I'm using FreeBSD 6.2
Stable,
samba version is 3.0.25.a. Sample smbd logs:
 
[2007/08/21 16:49:39, 3, effective(0, 0), real(0, 0)] libsmb/
ntlm_check.c:ntlm_password_check(455)
  ntlm_password_check: LM password, NT MD4 password in LM field and LMv2 
failed for user xxx
[2007/08/21 16:49:39, 3, effective(0, 0), real(0, 0)] smbd/
sec_ctx.c:push_sec_ctx(208)

Cheers.