not sure there is any "master browser".
One thing you COULD check...just for the heck of it...is on each machine the "services" that are running....like "server" and maybe "computer browser" and maybe even "network location awareness" (NLA)
I am sure you know it but you can run "services.msc" to see what services are set to start automatically and which are on manual or disabled....also you can see if they are currently started or not.
At
www.blackviper.com he has a guide as to which services you need etc etc and explanation of each
http://www.blackviper.com/WinXP/servicecfg.htm
I use pretty much the "safe" config he has listed.
ALso, do you have NetBios over tcp/ip enabled?
Are they xp home or Pro?
If Pro, do you have "simple file sharing" enabled?
I am sure there is a way to set the intervel to refresh the browser etc but not sure exactly how.
Are you pretty hip on dos networking commands etc? Can you see each comp there even when they dont show in network neighborhood?
by using "net view" for example.
ALso, cant you just cause a browser refresh by refreshing the net neighborhood window?
JP