Same problem for me. Game crashes all the time. Sometimes it shows up the default "Application stopped workin.. blah.. blah.." but sometimes is just closes and jump back to desktop without any notification.
I have all ther newest drivers, no 3rd party ARMA addons, vista home basic with visualization set to max performance, intel e6750, 2gb ram, wd raptor hdd, 8800gtx; x-fi sound card...
So I think i have all the stuffs that expect this game to run properly but it crashes on my system continuously. The only thing I figured out if I decrease visual settings to low/medium in the game it crashes "only" in every 1-1,5 hrs. As if it made some memory leak or something. It seems to me as if this game was still a beta release despite the several patches that already came out for this buggy game. I'm a developer myself but if i released a product like this i would be in serious trouble. And my repuation would be nowhere...