Multithread server using MPI

Hello,

I'm implementing a server in MPI that accepts more than one connection
from clients at the same time.
For do that I used MPI and pthreads.

What I want to do is a server that stays in a infinity loop waiting
for connections (MPI_Comm_accept(****tMD, MPI_INFO_NULL, 0,
MPI_COMM_WORLD, newCommClient);). When a connection is established, he
creates a new thread and return to wait more connections.  That means,
the server and the thread will work in parallel.

The function that the thread will execute calls mpi functions, like
MPI_probe, MPI_Get_count, MPI_Recv, MPI_Send,  MPI_Pack and
MPI_Unpack.

The problem I'm having is that the server and the thread are not
working in parallel successfully. Sometimes, the program hangs, do
nothing, and in another times a fatal error appears.

When I put the server to sleep for a moment, before he will wait
another connection, during the time he was sleeping the created thread
works fine. Once the server wakes up and starts to wait for a
connection, things stop working.

A peace of my code (Server):
-----------------------------------------------------------------------------------------------------------------------------
// arguments passed to a thread
typedef struct
{ MPI_Comm communicator;
  char * path1;
  char * path2;
  char * ****t;
} ThreadParam;

 pthread_t threads[10];
 int t =0;
 int rc;


 ThreadParam * listParam = NULL;
 MPI_Comm * newCommClient;


  /* server  infinity loop */
 while (time_out > 10)
 {

     newCommClient = malloc(sizeof(MPI_Comm));


     /* waiting for a connection */
     MPI_Comm_accept(****tMD, MPI_INFO_NULL, 0, MPI_COMM_WORLD,
newCommClient);

     listParam = malloc(sizeof(ThreadParam));

//with this communicator the thread will talk with
the                                                                       
                                                                           
                //
client
     listParam->communicator = *newCommClient;
     listParam->path1 = argv[2];
     listParam->path2 = argv[4];
     listParam->****t = ****tMD;

     rc = pthread_create(&threads[t], NULL, threadfunc, (void *)
listParam);

     if (rc){
         printf("ERROR; return code from pthread_create() is %d\n",
rc);
         exit(-1);
     }
     //sleep(1);
     t++;
  }

-----------------------------------------------------------------------------------------------------------------------------
Please, I need help to solve this problem!!

Thanks very mych!

Gisele