After completing Dead Money when I try to fast travel it says "Unable to fast travel from this location". If it helps, after I got out of the abandoned bunker I walked north to Nelson where I was asked to see Dead Sea. After that I left and walked up the road and was stopped by the NCR guys at the top of the hill. After that I tried fast traveling and I got the "Unable to fast travel from this location" message. I then walked to Novac and tried fast traveling from there, but still got the message.