I was just walking around inside the terminal at Fort McCarran, I walked around a corner and the two NCR officers by the back door (to the the Mojave Waste) just turned red on my radar and then started shooting at me for absolutely no reason. I'm on really good terms with the NCR, and I didn't steal anything or attack anyone. There was no reason for them to start shooting at me.

The door seems to be something you're not allowed to access yet. If you get too close to it they open fire.

It's not a glitch. You are not meant to access that area, I think. I just put on an NCR uniform so that I could go in. One person said "I'm not sure you're allowed in here" but other than that I was able to explore.

Yeah, I've been fooling around with it, and you guys are right, it's not a glitch it's just bad prgramming. In Fallout 3 anytime you weren't allowed in an area the dialogue screen would come up and they would tell you so. Then they would give you a few seconds to clear out, and if you didn't they would start shooting. Here, they just open up on you, no warning, nothing.