crashing when xydusa dies

When I finally hack my way to xydusa, the naga's death, the game crashes.
It is the same sort of crash that happens periodically, but in the other cases I just reboot and it works fine.

I've saved the game one hit away from her dying and have repeated the results under different video resolutions and with the sound off and things.

Any thoughts? Is there a different way to kill her than just hack her to death?

thanks