[Samba] Samba 4 - disconnection after 10 hours

[X-Dimension]

We have a strange problem since we are using Samba 4.
On our domain controller (Samba 4.1.4) we have a share called "programs" 
where we have installed
all programs that our employees need.
When a domain user (Windows 7 client) is connected round about 10 hours  
to our Samba DC,
all open programs that are installed on the "programs" share seems to 
get lost the connection to
the server and so they crash. We can only close these applications by 
killing them with the Windows task manager.
After this we can start all of these programs without a problem and 
there are working fine again.
It looks like Samba kills the connection after 10 hours although the 
programs are still in use.

Does anybody has the same problem, or knows what goes wrong here?

Thx for help!