Crash number 1:When joining the game, your loading bar gets stuck halfway and will stop loading, after a while your ArmA 3 will stop working.
Solution:
Go to your windows search bar and type in %AppData%
Now you'll see this in the top left corner:
Click on AppData.
Now click on Local and after you did this search for ArmA 3.
You'll see this:
Delete the MPMissionCache folder completly.
This will clear your Multiplayer Cache and will make you re-download the mission file. Usually this will fix everything.
After you've deleted this folder, start up ArmA 3 again and re-join the server. You will be able to join again.
Crash number 2:Frequently getting kicked for the error: Steam Ticket check failed: (null)
Solution:
First, you want to locate your Steam Directory.
In my case that is:
Now you want to click Common and look for ArmA 3.
After you've done this you will delete PhysX3_x86.dll
After you've done this, go to Steam and rightclick on ArmA 3 and click Properties. Then go to the tab Local Files and click the button that tells you to let steam verify your game for missing files.
Once this is over, you got a brand new .dll file and you are ready to go!
Hopefully this will help you all out.
Reference:
http://www.gaming-asylum.com/forums/index.php?/topic/22209-for-anyone-who-experiences-arma-3-crashes-the-solutions-are-here/