Please report found bugs and fatal crashes caused by X-Com Files here.
Each report is a save, with a description of what to do to get a crash. Ideally something as simple as "press end turn, shooting happens then the game crashes". Try to make a save as close to the crash as possible (i.e. just before pressing end turn) so that testers don't have much to do.
Extra info that is useful:
1 - Screenshot of the offending unit.
2 - Info about the offending unit and how to circumvent the bug.
(And yes, I stole most of this text from Arthanor's opening of a similar topic in X-Piratez. Hey, I'm a modder after all.)
EDIT: Changed the topic to make it look different from the Piratez one, as I was getting confused.
EDIT: Do not enable Aliens Pick Up Weapons, as it is already included with this mod.