No logon servers or Error Looking up domain groups

[global]
 
## Browsing/Identification ###
   workgroup = TESTDOM
   server string = %h server (Samba, Ubuntu)
   dns proxy = no
 
#### Networking ####
 
#### Debugging/Accounting ####
   log file = /var/log/samba/log.%m
   max log size = 1000
   syslog = 0
   panic action = /usr/share/samba/panic-action %d
 
####### Authentication #######
  security = domain
   encrypt passwords = true
   passdb backend = tdbsam
   obey pam restrictions = yes
   invalid users = root
   passwd program = /usr/bin/passwd %u
   passwd chat = *Enter\snew\sUNIX\spassword:* %n\n *Retype\snew\sUNIX\spasswor$
 
############ Misc ############
# You may want to add the following on a Linux system:
#         SO_RCVBUF=8192 SO_SNDBUF=8192
   socket options = TCP_NODELAY
 
#======================= Share Definitions =======================
 
[printers]
   comment = All Printers
   browseable = no
   path = /var/spool/samba
   printable = yes
   public = no
   writable = no
   create mode = 0700
 
[print$]
   comment = Printer Drivers
   path = /var/lib/samba/printers
   browseable = yes
   read only = yes
   guest ok = no
 
[public]
comment = Public Share
path = /home/shares/public
valid users = @users
force group = users
create mask = 0660
directory mask = 0771