Samba server sometimes disappear from network neighborhood

[Slamet Cahyono]

Hai folks,
I've installed samba for our company.  The vesrion is  1.9.16p9 and I've
tried to install the new version either 1.9.17alpha5. I have run on alpha
1000 unix version 4.0. We are using NT 4.0 for our login server (Domain
Controller). There three server samba in our company. All the configuration
is the same, but the last two server that have installed didn't appear in
the network.
Our client is W'95.
I'll appreciate for your help.

thanks
slamet