I've had the NCR guards in the subway located in New Vegas go bonkers on me for no apparent reason.
Zoned in (weapons were not out mine were holstered) and the shooting started. Killed about 8 of them and by the end of the fight there were two or three running
around with hands over their heads. I left them alone and holstered weapons as they were not hostile.
Few minutes passed and the survivors went back to their posts in the subway and all was cool.
A pile of Dead NCR and they dint' seem to give a flip.
I saw a faction pop up that I was reviled or some such flop by the NCR as a result of my dastardly deed.
However, despite that alert when I moved on I was not bothered by any NCR.
The faction thing is BORKED. I predict a mess of bugs tied to it. Good luck sorting it out.
Oh, yeah, and PS. I was not wearing any gear that should have triggered those guys.