I've gotten this bug problem. I have Veronica and ED-E as followers, and I was on my way to Caesar's tent to meet him when I was told by a guard that I had to enter the tent alone, and leave my followers alone. I told ED-E to wait, and only then realised Veronica wasn't there. I tried waiting outside the tent for 3 x 24 hours with no luck. I then fast travelled the 188 and waited 24 hours there, but she wasn't there either. I read on the wiki that she sometimes disappeared and so I should fast travel to the place where I lost her, so I fast travelled to the C. Grove place, but nothing. I then reloaded an earlier save, as I had saved just before accepting the boat ride to the Fort, but to my horror I realised she wasn't there either! So I have lost her earlier, without noticing. I have no idea where. I haven't dismissed her, and I still have her perk.

The problem is that since I can't tell her to wait, I can't enter Caesar's tent and continue that quest. So my questions are:

1. Are there any other tips to try and recover her?
2. Can I complete the game without doing that quest? (I have no plans on siding with CL anyway)

I haven't played through the game before, so I would appreciate as spoiler-free answers as possible. Any clues on what to do? Thanks!

First of all, check if you still have her companion perk. If you do, head to vault 22 (If you have discovered that location yet. If not, look it up in the wiki) and use the elevator there. When you use the Elevator, the game automaticly runs a companion check. Which means that the companion you are looking for will show up if you use the elevator. It really works, because I've tried it myself.
(please do note that this only works with active companions, so e.g. Boone can't be found this way if Veronica is your active humanoid companion)
Hope it helps

Thanks, good tip!

That's more complicated than I'd be prepared for. Assuming Veronica doesn't show up on the world map, I'd just go back to an earlier save (even one where she isn't following you but when you can find her at the 188), hit the console (the ` or ~ key, but hit `), click on her for her PRID, then load the latest game (you did save before you started this I hope) and type:

PRID xxxxxxxx (that's her number)
moveto player

Then for good measure, I would move around and make sure she runs after me.

This worked once when that old prospector dude from Goodsprings decided to walk on out to Black Mountain and I was wayyyyy too low-level to tangle with Super Mutants

Sorry, I forgot to mention I'm on PS3.