[Samba] Windows 7 logon script not executed

[List Mik]

Hello,

the configuration below, works like a charm for WinXP Prof. Clients:

samba 3.5.6, configured as PDC, netlogon share, logon script is 
users.bat. The primary group of the Domainusers is "users".

the relevant parts of smb.conf:

logon script = "%G.bat"
[netlogon]
         path = /home/samba/netlogon
         public = yes
         writeable = no
         browseable = yes
         valid users = "@Domain Users","@users"

Logging in from WinXP Prof. SP3 machines,  the logon script is executed 
without problems.
Logging in from Win7 Prof. SP1 machines (as same domain user), does not 
execute the logon script.

Domain logins from Win7 Pcs in general work, roaming profiles as well, 
only the logon script is not executed.

here comes the log of the logon process (/var/log/samba/log.testpc):

[2013/03/11 11:11:41.889891,  1] smbd/service.c:1070(make_connection_snum)
   testpc (::ffff:192.168.100.100) connect to service profiles initially 
as user testuser (uid=1011, gid=1001) (pid 17853)
[2013/03/11 11:11:41.930769,  1] smbd/service.c:1070(make_connection_snum)
   testpc (::ffff:192.168.100.100) connect to service profiles initially 
as user testpc$ (uid=1064, gid=515) (pid 17853)
[2013/03/11 11:11:41.932278,  1] smbd/vfs.c:932(check_reduced_name)
   check_reduced_name: couldn't get realpath for testuser.v2/ntuser.ini
[2013/03/11 11:11:42.312102,  0] smbd/nttrans.c:2204(call_nt_transact_ioctl)
   call_nt_transact_ioctl(0x1401c4): Currently not implemented.
[2013/03/11 11:11:43.082440,  1] smbd/service.c:1070(make_connection_snum)
   testpc (::ffff:192.168.100.100) connect to service testuser initially 
as user testuser (uid=1011, gid=1001) (pid 17853)
[2013/03/11 11:11:43.174407,  1] smbd/service.c:1070(make_connection_snum)
   testpc (::ffff:192.168.100.100) connect to service netlogon initially 
as user testuser (uid=1011, gid=1001) (pid 17853)
[2013/03/11 11:11:56.462383,  1] smbd/service.c:1251(close_cnum)
   testpc (::ffff:192.168.100.100) closed connection to service profiles
[2013/03/11 11:11:56.465834,  1] smbd/service.c:1251(close_cnum)
   testpc (::ffff:192.168.100.100) closed connection to service testuser
[2013/03/11 11:11:56.466887,  1] smbd/service.c:1251(close_cnum)
   testpc (::ffff:192.168.100.100) closed connection to service netlogon
[2013/03/11 11:12:08.458230,  1] smbd/service.c:1251(close_cnum)
   testpc (::ffff:192.168.100.100) closed connection to service profiles

Somehow it seems, that the win7 clients, when they do a domain logon, do 
not consider the group "users" as primary group of the domain user.

Any help appreciated, thanks

Mik