So i've encountered a couple of problems, most of which i'm almost certain are not the multiplayer's fault as it's just something that can happen in the actual game
1: I'm in windowed mode and i've been killed, i go to the steam chat window by alt tabbing out to it, but then i was stuck seeing the game over menu and i couldn't do anything to fix it until i just started mashing keys and then i went back to the chat and then back to the game by clicking on it, and then i was able to join back in
2: Accidentally alt tabbing out of fullscreen mode puts it in windowed mode, kind of a bother though (see #3 for more details), so i alt enter to go to full screen and discover a 'fullscreen windowed' mode that can't be chosen from the options menu
3: Though many of the game's scripts are being modified for this multiplayer, i'm still holding some of these problems against Just Cause 2 as i've said previously, the windowed mode leaves the taskbar overlapping the game, i accidentally hover the mouse over the 'show the desktop' thing Windows 7 has, and then i was no longer focused on the game but instead some random window
4: I was shooting some piece of wood i found and while shooting it, i tried to do the melee with the Q key while shooting, and the game crashed
Tl;dr: Just Cause 2 needs better windowed mode where the taskbar doesn't overlap the game and the multiplayer beta crashed while i was shooting and meleeing a piece of wood