Same me. After drinking some water from cantine, when I was drenched I got hypothermia and I died while running to heat myself.

Perhaps it was room like this?
http://feedback.dayzgame.com/view.php?id=8890

Exactly that happened to me twice. And not on the stairs but when passing thou the doors inside the buildings (house and police station on Svetloyarsk). First was the game freeze, than I was on the floor with broken legs, and my pants and everything inside was ruined.