Summary:
Arma 3 crashes when starting a multiplayer server and there are metadata files from OS X in the MPMissions folder. For example if Mission.Stratis.pbo is copied to that folder under OS X, a hidden file named ._Mission.Stratis.pbo is created. When Arma tries to process this file, there is an immediate Crash to Desktop. On the first re-launch of Arma, it crashes again. However on the 2nd attempt, it launches again and everything is fine.
{F17546}
Workaround: in Windows, make sure to delete any hidden ._* files which exist in that folder
More detail:
I am playing Arma 3 on my Retina MacBook Pro under Boot Camp (which runs beautifully, btw). As I am switching from OS X to Windows only to play Windows-only games, I have copied some MP Missions to their respective folder while still in OS X. In order to preserve HFS-metadata on non-HFS filesystems, OS X creates hidden ._filename files.
ARMA 3 does not support OS X . This is not happening on supported operating systems.
Closing as this is not Arma 3 relevant issue. I recommend you to not access any Arma 3 files under OS X and only access Arma 3 folder when running Windows 7 OS.
I hope you understand this. Thank you