CitcomCU mpirun not exiting cleanly

I am using CitcomCU on OSX Leopard which utilizes mpi, and it runs just fine and outputs all the data I need, but when it is finished it gives the average time for each timestep and then stops. Regardless of how long I wait it does not return to the command prompt. If I CTRL+C it says "^Cmpirun: killing job..." and then returns to the command prompt after 10 seconds or so. I seem to be getting all my data correctly but does anyone know why this may occur? I'm completely new here but I was hoping somebody could help me out. Thanks so much in advance.