I've been having a problem where Arma 3 suddenly crashes on launch every time. Gives the BI screen and windows notification pops up saying Arma has stopped working.
First 2 times this started happening i ended up formatting my pc and reinstalling windows (7) completely. It would run for a while and then it came again. Once it started doing this arma would never work anymore. I tried reinstalling physx, 3d drivers, Directx, steam, arma itself, nothing worked. Finaly i found the problem out of this forum post:
http://www.free-track.net/forum/index.php?showtopic=3599&page=1
as mentioned by this person, it is for me aswell, simply having freetrack installed makes arma crash on launch.
Hope this is of help to anyone.