While we're reporting FtN crashes here...
I was in Arena mode testing out the Xenomorph mod, seeing how it would run, how Xenos fared against other monsters, etc. I spawned a Vampire Lord (or ancient vamp, I don't recall perfectly), with steel plate and axe against a bunch of xenos. Vamp had no skill in axes, but limbs were flying and acid was splattering non the less.
long story short, I was trying to check if the blood was affecting the Vamp Lord and accidentally hit "preferences" instead. DF crashed. It was probably due to the mob not being meant to be viewed via Fortress style like you would with dwarves, to see labors and everything.
EDIT: Huh, tried recreating it in Arena mode. I can view ancient and lord preferences just "fine" as in it is just a blank black screen. No crash. May have been the xenos messing stuff up codewise.
EDIT2: For kicks, I let the naked Vamp Lord and Ancient Vamp fight it out along with 10 praetorian xenos (strongest xeno tier). The 10 xenos started tearing each other apart while the vamps started clawing each other.
Believe it or not, the vampire lord came out on top, but only because the ancient vampire tried strangling a fellow vampire to death.
EDIT the 3rd: Now I'm trying to kill off the Vamp lord with xenos. The lord actually bit a xenomorph and sucked its acidic blood. The xenomorph then used its new found vapiric powers.
Vampire Lord 1 bites Xenomorph 1 in the left lower arm, fracturing the bone!
Acid blood is sucked out of the wound!
Vampire lord 1 latches on firmly!
Xenomorph 1 stares!
Xenomorph 2 turns a bit green!