This is a repeatable, consistent bug causing a network connectivity/disconnect error + temporary freeze.
In the server browser in the PC version 1.1 of Crysis 2 when you try to filter in the "Join Match" area the program freezes, console says:

CGameBrowser search for sessions error 80
CCGameBrowser::MatchmakingSessionSearchCallback DONE
[Lobby] EndTask 12 (12) Error 80
[Lobby] Start SessionDelete error 0
CGameBrowser::CancelSearching

"An error has occurred, please check your network connectivity"
error, freezes the screen for about 30 seconds, to the point where although music plays, the background texture behind the text in the list is frozen in the middle of its animation to stretch all the way to the right border of the list (halfway across, frozen). Then it comes back to life later with the error dialog.

This happens despite first doing an unfiltered search and getting 1236 results [really Crytek, who needs to *see* 1236 results, eh?] ... If you then FILTER the search to say, no empty, no full, not password protected, ranked (or not ranked, doesn't matter), then you click Done, then you click 'Cancel'/'Refresh'... Kaboom!

While you're at it, can you please include a little menu item somewhere that saves your last 3 filtered searches so you don't have to do them over and over and over every single time you log-in to the game? If I go through the trouble to filter, why do you force me to do it over and over and over again instead of just letting me click a button that says "My Low-Ping Filter" and be done?

This would be less annoying if I could actually PLAY a multiplayer match (which I still have not been able to do since I bought several copies of the game because the multiplayer browser/network code is broken).
=(

Not many Crytek employees are going to read this, so best thing to do is report it here: http://www.gamesas.com/support/ Crytek's support are paid to listen and if many of them see's the same issues the priority of the issue will raise and the support team will pass the word onto the developing team.

I'm putting it here in case other people are having the same problem, so they can comment and perhaps add to the report. Keeping it 'private' only means it's buried somewhere useless. The squeaky wheel gets the grease.

[ Bump. ]

Servers "NL Clanhost #10" and "NL Clanhost #7" managed to get me playing without a problem in 1.2 patch.
The bad news is that the server browser is riddled with bugs and I have not been able to play a game outside those 2 servers (which I filtered-to by name to successfully play).

Crytek, LOOK AT THOSE TWO SERVERS and figure out how they are configured vs the rest, because THAT FIXES THE PROBLEM (or so it seems on 2 of my machines).

"Join Match" is still a problem in 1.2 patch. Multiplayer browser still freezes when you filter or cancel or refresh, then logs you out. It's a bug-ridden mess and the error messages are COMPLETELY USELESS at the moment.