diff -dur mpi/communicator.hpp mpi_new/communicator.hpp
--- mpi/communicator.hpp	2012-01-22 20:41:50.589783507 -0600
+++ mpi_new/communicator.hpp	2012-01-22 20:47:46.537557362 -0600
@@ -871,7 +871,7 @@
     {
       int finalized;
       BOOST_MPI_CHECK_RESULT(MPI_Finalized, (&finalized));
-      if (!finalized)
+      if (!finalized && MPI_COMM_NULL != *comm)
         BOOST_MPI_CHECK_RESULT(MPI_Comm_free, (comm));
       delete comm;
     }