Computer Browsing on NT 4.0

[qjones` 0]

I have an NT 4.0 Domain with 23 servers. The PDC and BDC are the Master Browser and Backup Browser respectively with no other Servers/Workstations running Computer Browser service. The Problem is I have 4 Productions Servers that run Terminal Server with all current SP and hotfixes with Metaframe 1.8 and at peak user login times each of these 4 servers disappear from the browse list in Network Neighborhood, Server Mgr, etc. It starts once any of these servers gets to close to 30 users and at the end of the day when users are less the servers reappear in the browse list. All these servers can be mapped to, pinged or name resolved but just doesn't show up in browse list and I need them to show in browse list for specific Administration with Metaframe during peak time. Any suggestions on what would cause this and a resolution would be greatly welcome.