BDC Browsing problem

I have a strange problem. I have a Domain with 3 servers (1 PDC & 2 BDC’s). Occasionally, the PDC becomes unable to “see” the one BDC. When I view the Event Viewer on the BDC, I see Netlogon and Browsing errors that start when the problem occurs. Restarting the BDC does not solve the problem– It can only see itself, and does not see the existance of the rest of the Domain. However, rebooting the PDC clears up the problem for a while. Any Suggestions?