Ok, here's the report.

BTW, graphics card drivers were updated a couple of weeks ago: Card: nVidia GeForce GT 740, 1024 Mb GDDR5, D3D API v12
Drivers: v368.69

It was the game that crashed and stayed inactive (totally black screen not responding to mouse or keyboard); only could ended it from Task Manager. But Launcher stayed in the backgroud showing its main screen, and appearing quen arma3.exe was terminated. It may be (is just a suspicion) Launcher wanted to show a dialog but arma3 program was in control of screen.

Got another similar crash, always in Tanoa, but different situation. This time was running cross-country at night, on plain, when hapened.

5. the more affected weapon is main gun, not pistol or LAW

6. hapens the same when unloading a crate (i.e. Support crate)from a Quad

I will add that Marksman class should have a more stealthy presence, i.e.: AI to have more dificulty to spot them. They are suposed to use Gillie suits, don't they? May be not ...