The only clue that I have got is this:
I think the problem is that my graphic drivers can't handle DayZ too well.
I tried to join a server and the first thing I did was to lay down and just stare in to the ground. In that way, not too many textures had to load and the graphic drivers didn't have to work so much. I was able to stay in that position forever. I had it going for one hour. After that I rised and started playing normally, and once again, after about 30-40 min, DayZ crashed.
All of this was made on the stable branch, never on the experimental branch.