[Myrinet] application hangs when using 'call system'

I am in the process of debugging an application that appears to hang 
whenever a Fortran call to 'system' is made. In the following example code:

---[cut here]---     
       include 'mpif.h'                                                   
                                                                        
      integer :: time_array0(8), time_array1(8), taskid                  
      character*50 scom                                                  
                                                                        
      call MPI_INIT (mpierr)                                             
      call MPI_COMM_SIZE (MPI_COMM_WORLD,numtasks,mpierr)                
      call MPI_COMM_RANK (MPI_COMM_WORLD,taskid,mpierr)                  
                                                                         
c                                                                        
      write (scom,600) taskid                                            
      call system (scom)                                                 
 600  format ('echo This is task ',i3,' on `/bin/hostname`')             
c                                                                        
      call date_and_time(values=time_array0)                             
      write (6,601) taskid,time_array0(2),time_array0(3),time_array0(1), 
     1 time_array0(5),time_array0(6),time_array0(7)                      
 601  format (' starting taskid=',i3, ' date & time is  ',i2,'/',i2,     
     1        '/',i4,2x,i2,':',i2,':',i2)                                
c                                                                        
        write(*,*) 'Starting MPI_BARRIER: ', taskid                      
        call MPI_BARRIER (MPI_COMM_WORLD,mpierr)                         
        write(*,*) 'End of MPI_BARRIER: ', taskid                        
                                                                         
        call MPI_FINALIZE (mpierr)                                       
                                                                         
      end 
---[cut here]---

the code will hang and never return from the MPI_BARRIER call.

If the line 'call system (scom) ' is removed, the code will run 
normally. (The system call is for example only. I know I can use the MPI 
hostname call to obtain the host id!)

I suspect the 'system' call is somehow upsetting GM. Any ideas (other 
than eliminating any calls to system)?

GM build ID is "1.5.1_Linux [email protected] Tue Apr  9 08:07:01 
EDT 2002." and compiler used was PGI's f90.

Thanks,

  --Jeff