It has never happened to me so far while I was playing in DayZ.

it has happened to me in berezino more than once, and recently on one of those watching towers in the NWE airfield.

I died twice when trying to climb up a ladder, for no apparent reason. First time I was climbing (didn't stop) and about midway the screen went black "You are dead". Second time I climbed to almost the top, stopped and looked around using "Alt"+mouse movement. After a second the screen went black "You are dead".

Please note that I did not see myself falling before I died, screen went blank while I was on the ladder, as if I was shot. However, I had a friend around in both cases and nobody else on the server. Friend said he saw my body fall to the ground about a second after I died.

happened in Cherno climbing ladder on to the highest climbable (industrial) building in town.

Was climbing up (about 1/3 of the first part) and double pressed alt so I could look left for screenshot while climbing. (you can't steam screenshot while alt is pressed, so double alt is the only way to take as screenshot while alt-looking as you won't have to keep alt pressed).

Anyway, I turn my head right, ready to make a screenshot. You are dead.

No sound, nothing. Just that. I pressed esc and I see myself in the grass (blackscreen dissapears for one sec if you 'esc' in and out of the game.

I have had this but it was going down and when i got to to the bottom i died and had broken legs... very annoying

Had this happen to me last night. Was going down a ladder, and stopped for a second halfway through. My legs broke and I instantly died.

Going up ladders also radomly kills your character.