Simple questions - where do the active servers (players playing in them) disappear from the match browser of Quake Live.
Quite often (read all the bloody time) I see a server I'd like to join, especially in less played modes like TDM or whatnot, but when the serverlist refreshes the server is just gone. One can refresh 10x over and over again but it is gone. One can limit the browsing selection to the specific game mode, region etc, but the server is just gone, although the game is still being played.
In about 5 minutes in appears once again with the same players as before, cause they've been playing for the whole duration of the "limbo trip".

Does anyone have any idea what might be causing this and how it could be avoided? Pretty often I can only join regular public server because someone in my friends list is playing in it. I can also watch that same server come and go in and out of the limbo while my friend is playing in it.