dalke mentioned some good examples. In our case, the most annoying problem we had was that the entire run would sometimes just hang. I'm not aware that the pro

dalke mentioned some good examples. In our case, the most annoying problem we had was that the entire run would sometimes just hang. I'm not aware that the problem was tracked down, but the author suspected some race condition in the MPI library that caused some message to get lost and thus some task to wait indefinitely.