[Samba] samba loses browse list

[Csere Matyas]

hello there

i have a very strange problem.

samba wins the local master / browser election as i can see from the logs.
it works fine for a couple of minutes (eg: all windowses are able to 
browse (all computers are win xp))
but after a while it sort of looses the browse list. and i cant see any 
computers on the network.
it is still the master, but with and empty browse list?

anyone can give me a hint?
thanks in advance
wd
ps: i've been able to do this with samba 2.x and 3.x too, my config is 
fubar?