[Samba] user 'root' does not exist

[Hamish]

Hello list
Sorry if this has been answered before, I have had a look around and 
could not find any answers.
I am running samba 3.0.3pre2 on suse 9.0 - installed from suse rpms.
I have managed to join the 2k3 domain and users are authenticating 
perfectly and all seems to be working, (users have actually remarked 
about a speed increase!) although i get this strange message in the 
log.winbindd:

[datetime, 1] nsswitch/winbindd_group.c:winbindd_getgroups(1023)
user 'root' does not exist

This can also be any other linux user that runs anything - i get one for 
postfix just before receiving mail.
Have i done something wrong in nsswitch?
in nsswitch.conf i made the following changes:

passwd: files winbind
shadow: files winbind
group: files winbind

Below is the [edited] general section if smb.conf

[global]
    workgroup = MYADDOMAIN
    realm = MYADDOMAIN
    server string = fred
    interfaces = 127.0.0.1, eth1
    bind interfaces only = Yes
    security = DOMAIN
    password server = SERVER.MYADDOMAIN
    preferred master = No
    local master = No
    ldap ssl = no
    idmap uid = 10000-20000
    idmap gid = 10000-20000
    winbind use default domain = Yes
    admin users = MYADDOMAIN\administrator
    printer admin = MYADDOMAIN\administrator
    read only = No
    ea support = Yes
    hide unreadable = Yes
    store dos attributes = Yes
    dos filetimes = Yes

Thanks!

Hamish