Hi, All, I just notice that in gmx_node_num() of network.c of version 3.2.1: int gmx_node_num(void) { #ifndef USE_MPI return 1; #else int i; return MPI_Comm_size(MPI_COMM_WORLD, &i); return i; #endif } Should the "return" before MPI_Commsize(...) be removed? and same problem exists in gmx_node_id(). Thanks.