[Samba] guest share on a " security = user" server

[Andreas Moroder]

> Andreas,
> 
> This is the place to start:
> http://wiki.samba.org/index.php/Frequently_Asked_Questions#guest_access
> 
> Dale

Hello,

I does not work for me. Maybe I have something wrong in the config I overlook.

My smbusers file:
nobody = guest

part of my smb.conf

security = user
map to guest = Bad User
username map = /etc/samba/smbusers

[openshare]
guest ok = yes
path = /san/san-lacie/
read only = no
writable = no
printable = no
Browseable = No

I tested with 
smbclient //server/public -Unot_a_user%foo

and it works. It does not work from windows because the user/pwd dialog
appears when I try to access the share from the explorer respectively gives
a error when I try from the console. 
It is important that it works without the need to enter a password, because
I have to access this share from  a program that is called by a service that
runs as NT-AUTORITY\SYSTEM.

Thanks
Andreas