You get a blue screen with a percentage going up to 100%(which is MS gathering some info presumably) and then your PC reboots.
"system thread exception not handled" something along these lines is the error message
Happened 2 times now, at random.
%appdata%/local/
Open steam.
Click DayZ.
Click Play.
Click Play (again).
PC crashes and reboots.
I just noticed, and this happened last time as well(didn't realise that it was connected), my whole steam config(settings like hotkeys and notification settings) are all reset to default. This might be a steam issue.