not sure yall have encoun tered this but take a http://www.youtube.com/user/Vebeez?feature=mhsn

Yeah that has happened to me before too. It happens when the area hasn't popped in (loaded) properly. You can just walk through all of the 2D renders, and then when they load you get stuck inside of them.

I had this happen with the hangar in Nellis Airforce Base. I just ran straigh through the wall, it popped in like thirty second later, and the only way out of it was to fast travel.

Dang that had to svck,guess you could say he was lucky