Since I've completed Veronica's quest in Hidden Valley, after taking care of the disgruntled Brotherhood members, she thanks me for helping her... and then she won't follow me anymore. Unless I dismiss her altogether she will stand absolutely still and not follow me. She'll warp with me, but then keep on standing still. I've tried everything I can think of and I just can't get her to actually follow me. She's gone unconscious, been dismissed and I met up with her later, told to wait several times, everything.

As soon as she thanks me, boom, she's rooted to the ground. Up until that she's totally fine.

What's going on? I'm guessing this is a bug... can it be fixed?

For a workaround after she has frozen, go to Gibson's Shack. Veronica will instantly appear when you enter. Use the computer and download the notes again. Walk outside and talk to her in normal dialog, tell her again what tech you will go for, and end the conversation. This seems to reset her and she will start to follow you as normal.

Excellent, thanks! That solved it perfectly!

I've got the same problem. I even released her to the 188 but she still won't follow me, even though she shows as a companion and I get the perk associated with her.
However, she has appeared 3 times so far! Once at the bottom of some stairs, and then outside when I went through the door, but she still wouldn't follow. Then she suddenly appeared near the end of combat, when she helped take out the main bad guy. Then again in the next combat against a group of bad guys.
This all happened in the same session, but I still can't get her to follow me!
I'll try the solution suggested above, and if that doesn't work I'll have to abandon her.

Thanks! It worked even though my bug started after Followers Outpost shooting.

Hopefully this, and Veronica's level (though easily fixed with a simple mod) are among the many, many, many things addressed by this patch that is supposedly done.

This'll fix her too.

http://www.newvegasnexus.com/downloads/file.php?id=35943