Greetings,

I just let Veronica show the Pulse gun to the Elder and left ED-E with the Scribe, exited the bunker and killed of the 4 paladins. She engaged in the fight and spoke to me afterwards, but now she just stands around, not even turning towards me. I was able to fast-travel to McCarran with her, but she didn't move from there. She didn't even fast-travel with me to Miguel's Pawn Shop. Is there a workaround to fix that?
Even when i retrieved ED-E from Primm did she not follow me.

I had Veronica glitch out on me after I convinced her to leave the BOS and join the Followers of the Apocalypse. We talked our way past the paladins at Hidden Valley and went to the Follower's Outpost. After returning the next day to the massacre and having the fight with the paladins there she would just stand around doing nothing whenever I traveled anywhere with her, and she wouldn't equip any weapons at all, even her default power fist.

All I could do was reload a previous save and try again - when I did that she behaved normally.

There is a bug that when you finish her quest she will sometimes stop following you.I think to prevent this you need to speek to her about it before she speeks to you,not sure though.
Also I don't no of any work arounds that fix this once it happens,your best bet is to reload a previous save.

Hmmm, I just tried as suggested, but it didn't seem to change anything. How far back do you guys think would make sense?

that happened to me too, this is another fix for it on 360 at least, go to the shack near novac, gibson shack or whatever, where that old lady is, there is ashack real close by, go to the shack and and she will appear there with you, then you need to go in the shack and re download the info again and then talk to her and she will follow you again, this is an official fix for that glitch and it worked fine for me.

This did not work for me. I went to the shack. I downloaded from the terminal. Veronica appeared. She talked. But then, I could not terminate the conversation (no phrase like "good-bye" ever appeared and all I could do was continue to ask her for info). So, I loaded a recent game and tried to make her wait for me (NOTE: she would always "fast travel" with me, but would never move locally with me). She went into waiting mode and I left to do some work at another location. After a while, she suddenly appeared again and began the same dialogue that had no ending. That dialogue is the one where she tries to get me to select one of three things to pursue.

NOTE: I had already finished the Helios quest and chosen to not set up Helios as a weapon. That option was clearly no longer available and she tells me that that is too bad, but I should choose one of the other two. Maybe if I had not finished the Helios quest the way that I did, Veronica would have been happy and been reestablished at the shack.

Thanks for the info guys. I experimented a little and the save from right before talking to McNamara worked. She is currently following me, hopefully she'll continue to.