I'm running samba-3.0.21b on gentoo. All authentication against a new 2003 active directory is working fine as far as I can tell bu I have come across an unusual thing, see below:

hari@test2 ~ $ id
uid=10005(hari) gid=10000(Domain Users) groups=10000(Domain Users),10008(Domain Admins),10009(UnixAdmins),10010(UnixAdmins)

For some reason the group UnixAdmins has been listed twice and given two ids by winbind. This group has not been recently added, I haven't deleted and readded it or anything like that. I've restart samba(smbd nmbd and winbindd) and logged back in with this domain account and I get the same result.

Below you can see my entire smb.conf:
[global]

   workgroup = MYDOM
   realm = MYDOMAIN.COM
   server string = Samba Server %v
   log file = /var/log/samba/log.%m
   max log size = 50
   hosts allow = 192.168.1. 192.168.2. 127.
   map to guest = bad user
   security = ADS
   password server = myserver
   encrypt passwords = yes
   winbind use default domain = yes
   template shell = /bin/bash
   socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192

 idmap uid = 10000-20000
 idmap gid = 10000-20000

[homes]
   comment = Home Directories
   browseable = no
   writable = yes