[Samba] some users cannot login on some machines

[yeno at gmx.net]

Hi. After an crash and reboot, some users can't login on some machines.
There are running Samba 3.0.6 as a PDC with W2k-Clients only. If someone 
logs in on a machine he has once logged in before, he comes in. But if 
someone tries to log in an a machine that contains no local copy of the 
roaming profile, the user will be rejected. in the first days, there was 
another message: "an attached device could not been found".
If i try smbclient -L \\samba-server -U user  , I pass.
Even I can't add a new machine in the domain (usual way: net use * /d, 
then in the window networkidentification change from workgroup to Domain,
answer the user/passwort phrase with root/<password>   -> access denied).
There are no changes at the smb.conf since months so I don't think there 
is a problem.
On the way to track down the problem I stumble over my 
group_mappings.tdb.  All mappings points to -1. In my opinion, the 
Domain_users have to point to the unixgroupusers and the Domain_admins 
have to point to the unixgroup admins (self-defined unix-group).
But if I set this up (net groupmap modify ntgroup="Domain_Users" 
unixgroup="users") nothing changes. (exept the admins can add/del 
Domain-Users from certain NT-rights).

Has anyone out there an idea?

greetings
Andy P.

Sorry for not posting any logs or files. I'm writing here from home and 
have no connection to the Samba-Server at the moment.