I have suddenly come across a problem with my companions. I had hired Boone, Arcade Gannon, Cass and Raul without any problems and each one is currently waiting at the Lucky 38. However when I arrived at Jacobstown and attempted to hire Lilly I was told I could only have one companion at once. I cannot hire any other companions either.

Just eliminate things, I have not even met ED-E, Rex or Veronica in this playthrough. I have checked and double checked that I absolutely have no permanent companions following me or waiting anywhere. All four are waiting to be recruited in the Lucky 38.

The only thing I could remember happening before these problems started was that I had an NCR Ranger follow me through the Emergency Radio. This Ranger disappear so I dismissed them. Any help and advice would be appreciated.

Xbox 360 user also.

This might not be it, but could it be one of your companions inside the Lucky 48 is not in fact dismissed but in "Wait here" mode?

To be safe go to lucky 38. If they are there find them, dismiss them to original spot you found them.
I currey can't get Raul to fix anything even in his shack.