I'm on the quest where Bennys at the fort and I follow him and try to get the platinum chip, only problem is he's been captured and Caesar has the chip so I go to talk to Caesar but it zooms in for about 3 seconds and zooms back out again and I've tried over and over again to kill him or pickpocket but its just not working and he never sleeps!! can anyone help its driving me crazy?!

Maybe your reputation with the NCR is too high??
He might choose not to talk to you because of this.
Might just be a glitch, save and reload and try again.

Yea I have the exact same issue. I guess the 40 hours I put in to get to this point were wasted because I can't progress the main storyline anymore.

Make a save file and then go kill a bunch of NCR and see if that will fix it.

Also, review the quest log and make sure you are at a point where you can speak to him, there could be some small requirement in the Wild Cards mission tree you have unfinished that is stopping it,