browser issues nt 4.0

Network neighborhood sporadically loses computers. Usually all domain members except the pdc, and the bdc’s at remote locations leave network neighborhood. The browstat command says that it cannot find the master browser using the GetAdapterStatus. We reboot the pdc and the neighborhood is back to normal.
The last time this happpened, the bdcs were also gone. Rebooting the pdc did not restore the connection. Netdom revealed that the secure connection between the domain controllers was gone. After using Browstat to force an announcement, the bdc eventually came back. Why are we losing these icons in neighborhood? Are they not registering with WINS? Can losing these icons cause the secure channel between the dc’s to go down?