[Samba] Samba DMB "loses" machines in the Network Neighborhood

[Evan Hein]

I have a long running problem with my configuration of Samba as a domain
master browser. After nmbd comes up, all the machines on the network are
viewable in the Network Neighborhood as they should be. But about half an
hour later, Samba seems to lose track of several machines; they no longer
appear in NN or /var/cache/samba/browse.dat.

I recently upgraded to a packaged version 3.0.20b (for Slackware) trying to
fix the issue with previous 3.0.x version that was installed, but to no
avail.

The [global] block of my smb.conf:

[global]
        workgroup = 203

        security = share

        printing = CUPS
        printcap name = CUPS
        load printers = yes

        wins support = yes
        local master = yes
        domain master = yes
        preferred master = yes
        OS level = 255

        smb ports = 139 445
        interfaces = eth1 eth2
        bind interfaces only = yes
        hosts allow = 10.11.20. 127. 192.168.0.