Sometimes when you are walking around on a rooftop or on the second floor or higher of some buildings, you randomly start taking damage as if you had just fallen. This tends to happen repeatedly when it happens at all, as if you fall a small distance several times, until you eventually die, or get lucky and just break both your legs.
- Legacy ID
This most often has happened to me when climbing to the second or higher floor of fire stations. It has also happened when walking around the second floor of some regular houses, as well as on the rooftops of hospitals and police stations. I have absolutely confirmed that this is a real, genuine bug, because it has happened a number of times when no one is around, and it always results in my character's shoes and pants, along with everything else in the pants, to be ruined, while all the other items take no damage.
I consider this to be the most game-breaking bug in day z, even more so than the character wipe via server reset bug or the teleportation bug, because it is the only one that is completely unpreventable, but can result in your character dying.
One of the first things I would try, at least as a temporary fix to this problem, is to increase slightly the distance that a character has to fall before taking damage. The way the bug seems to work is it thinks that the character is falling a small enough distance that he doesn't immediately take lethal damage. Instead, the character takes damage repeatedly over and over, as if falling several times in a row. I'm sure there are other things that you can try to address the issue more directly, but at least this will make the game playable in alpha in the meantime.