[Samba] Servers disappear from Network neighborhood

[Philip Washington]

I am using Samba-PDC-LDAP with samba-3.0.20b-1.  On my file servers I am 
using samba-3.0.10-1.4. 
I'm not sure exactly what is happening but every couple of weeks the 
file servers disappear form network neighborhood.  I checked browstat on 
my Windows system and it points to my PDC as the master browser and I 
checked the wins.dat file on my PDC and the systems were there.  I did 
not check the browse.dat file before correcting this latest problem (by 
restarting the nmbd service on the systems in question).  Is there a 
relationship between samba versions and systems dropping out of network 
neighborhood?  What does this indicate when a system drops out of 
network neighborhood, is it not reporting correctly to the master browser?