I haven't tested it but I think it might be your head going into backpack or other clothing/equipment. I had this bug too but my screen went completely black. I had a mountain backpack equipped and I think I saw my head clipping into it before it went black.

This happened when going prone. No problems when crouching or standing.

Edit: similiar issue in http://feedback.dayzgame.com/view.php?id=1764 but with motorcycle helmet.

Have you tried only equipping your helmet (no backpack, mask or upper body clothing) and this is still happening?

Similiar issue in http://feedback.dayzgame.com/view.php?id=5175

They had screen streaks but I had completely black screen with gas mask, military helmet and mountain backpack equipped. Couldn't test which item was causing it because of random character reset.