I am trying to get the Community Earth System Model (CESM) [http://www.cesm.ucar.edu/] working on our Linux cluster; I was apparently able to build okay w/ no errors. However, when I try and run the model either using mpirun or just running the model executable directly, I get the errors:
0 - MPI_GROUP_RANGE_INCL : Invalid rank 1
 Aborting program !
(seq_comm_setcomm) initialize ID ( 7 GLOBAL ) pelist = 0 0 1 ( npes = 1) ( nthreads = 1)
 Aborting program!
p0_27915: p4_error: : 8262
As I am a Linux/MPICH/programmer newbie, I am really at a loss regarding how to begin debugging this error. Any suggestions / pointers appreciated! Thanks in advance!