Okay, now this is happenening to me, too, I think. I imagine it's a lot like Bug 957, where dwarves are tormented in their rest.
I have a marksdwarf who was shot by an orc sniper (from the popular orc mod); when people drag him to a bed to rest, his rest is immediately 'interrupted by an orc sniper,' but instead of spamming rest, he just lies there unconscious. He has a broken head and brain, mangled right hand and upper and lower legs, and lost a left eye and a thumb. He's only 'Very Tough', so I don't think he should be alive. He never gets hungry or thirsty, as far as I can tell.
I also have the orc who injured him captured in a cage (with no other orcs left on the map). I have tried the following disposal methods (with savescumming):
1) Throw the orc down a 15z fall. The orc dies, blows apart, and then the injured marksdwarf immediately (four or five steps later) bleeds to death
2) Throw the orc cage in magma. The orc disappears, the markdwarf bleeds to death.
3) Tried to trade the orc. Orc breaks out of cage, is killed by merchants, marksdwarf bleeds to death.
4) Throw the orc down a 15z fall while dragging the marksdwarf to a new bed. This one was extra interesting. The moment the orc dies, the marksdwarf starts to leave a trail of blood. After 5 squares of blood trail, the marksdwarf dies.
I think there's some version of bug 957 (discussed
http://www.bay12games.com/forum/index.php?topic=22890.0) where, instead of spamming 'rest' messages, the dwarf's metabolism just stops. I don't know how to test whether your bug is the same since you can't kill the offending party.