Hi,
at first, sorry for my english.
I have exactly the same problem, played on DayZ like 2 years, and since the 14/03/14 i can't join any server on any mod; Arma 2 OA in multiplayers don't works too.
I had tried everything, except formating the whole PC and reinstalling the OS like Seb.
I had played before the 14/03/14 and haven't any problem, my Windows Update was disable, nothing change between the 13/03 and 14/03 (no updates from windows, the game or anything else).
The game crash when I join anymods (vanilla too).
Seb, i was playing on the same mod of you (Origins 1.7.8.5) when this happened, but i'm out of idea... there is no game update since the 03/03/14 (1.7.8 > 1.7.8.5)... i really don't understand... and we have exactly the same problem and tried the same things...
If you find something, please tell me i'm really out of ideas....
Have a good day,
Fox.