Hunter Fuckwad Vabokzim is a retired adventurer who appeared in a migrant wave. Going to [ u]nits, then [v]iewing Fuckwad, then trying to check his [r]elationships will crash to desktop. (I'm running the Linux version on Ubuntu 12.04 64-bit, incidentally).

I checked some other dwarfs to see if any of their screens caused the same crash. Neither the expedition leader nor the manager (both from the original 7) cause it, nor does animal caretaker Id Limulurist (who has Fuckwad as a friend), nor do most of the others I checked. However, the broker Dumat Muthkatsosh (who is also a migrant, but not a former adventurer), DOES also cause the crash. Some of the other ones I checked that did not cause the crash were also migrants, so that's obviously not the whole story

Hope this helps. Please let me know if there's any more information I can provide.