I've just personally tested a work around for this issue and confirmed that it works. So if you're getting this issue please try the following:
1) Start Crysis 2 as per normal and get into the main menu.
2) BEFORE you click on "Multiplayer" (where the crash occurs), alt+tab back into Windows.
3) Open up your Network properties and disable your network adaptor. (instructions)
4) Go back into the game and click on Multiplayer, it should successfully load the next screen without crashing.
5) Alt+tab back to Windows and re-enable your network adaptor.
6) Go back into the game and start playing.
This issue is related to heavy firewalls that isn't allowing the game to communicate properly but that should sucessfully bypass the error and allow you to play online. A proper fix for this is coming soon but give this a go in the mean time and let us know your results!
Thanks!
EDIT: This error was fixed in Patch 1.2