At the begging when the 3 aliens are doing "stuff", 2 of them stop moving, but the third one is still blinking its eyes. When I hit the action button my character grunts, but nothing happens. The only other thing I can do is access the in game menu. Thanks and Merry Christmas!

Any mods active. See, with FO3Edit, if *DLC05MZ1QuestScript is overridden? That one, as I recall, was ...touchy.

*pretty sure that's the one