Hi,
Cifs got a problem with nat and more user accounts on one ip. There is a cifs option that you can try. the option is called cifs.client.dup-detection and is set default to ip-address Try name, for detection through netbios or set it to off Cifs client detection is a option to detect duplicate sessions in order to terminate any session that did not terminate when a client system rebooted
Hope that helps, greetz
Philipp