Additionally, consider setting a memory allocator parameter in your launch properties. Right-click on ARMA 3 in Steam, go to Properties, there should be a "launch parameters" or somesuch button. In the popup, enter "-malloc=system" which should clear up a few potential issues. Keep in mind you will have to completely close ARMA (including the launcher) for this to take effect.
If you're using a third-party launcher you can do this with that as well, but I don't know the procedures as I don't use a third-party launcher