samba - Feb 2012 - New Windows 7 PC in samba network sees itself as logonserver respectively can not access subdirectories

Hello,

we are preparing a new image for our windows 7 computers. We can connect 
to the domain, we also see all of our samba servers. On one server we 
can logon, see also the directories in the share, but when we try to 
open subdirectories explorer hangs for a long time and then a dialog 
appears telling me that I probably don't have the rights on this directory.

The only strange thins I see in this PC is that the environment variable 
LOGONSERVER is set to the name of the PC itself.

On this server on the share we want to access we have set
     force user = wwwrun
     force group = nogroup

I tried via ssh to cd to the directories I want to go via samba and I 
have enough rights as wwwrun

All works well from all our XP and also older Win 7 computers.

Can anyone please help me.

Thanks
Andreas