[Samba] password issue in zentyal samba 4

[antonello facchetti]

I've set up a system with a zentyal 3.0.26 samba 4 server.
I've got win7, winXP, ubuntu 12.04 clients.
Users log on the win clients correctly.
On linux clients when users log on the second time I got a warning 
message saying that the password will expire and have to be changed in  
a short period of time and the system hangs, thus not logging in.
I don't want password to have any expiration time, but I couldn't find 
where to set this feature on the zentyal dashboard.
Moreover, I don't have this issue on the windows clients, so I may think 
that the issue is due to the linux system on the client side. Still I 
don't know how to cope with it.

Antonello