Having the same issue (CTD with error code c0000005) since ~23rd of march
No start possible since then - even with switch back to stable branch.
Up to ~ 16th I was able to play first the stable branch and then the developers branch.... didn't play in between.
Since then there were some updates of arma3 - but without help.
Once i aded the -nosplash startup option, it is most of the time the moment after the steam overlay info fades out in fullscreen while still showing the aram3-icon. Sometimes it crashes even before teh steam info si shonw (while aram3-logo is shown)

I also checked the recent Windows updates since match 19th - there was only kb2929755 added (besides windows defender). But rolling back that update and rebooting did not help either.

Trying to reinstall the whole game to stable branch now and hoping for a fix.
Seems like one of the updates around 23rd broke it!?
Is there a possibility to get a testinstall of say the developers brnach from 16th of march and try to run this?

Added my crash reports too, hoping it is really the same issue (my GPU is an ASUS HD7790 drivers are latest and unchanged).

Found it on my PC:
I needed ot DEINSTALL the program FastTrack!!!
(I was not even runnning it - just beeing installed on my PC seems to have caused the problem!)

Hope it is as easy for you, too!