ubuntu desktop 12.04 lts on nehalem workstation

[Roger Miller]

I recently installed ubuntu desktop 12.04 LTS on a workstation equipped
with 12 GB of RAM and 2 Xeon 5600-series processors, each with 6 cores.
This may not be the kind of equipment that the software was designed
for, but I was in a pinch for time.

I am doing groundwater simulations using a widely used and very stable
FORTRAN code (MODFLOW-2000).  The code compiles with or without MPI
support (using either openMPI or mpich2) and reports no problems.  The
simulations fail, reporting impossible problems that suggest to me that
the memory is being accessed incorrectly.

The same code compiled on an older computer runs on the workstation
without problems as long as I am not using MPI.  When I try to run the
simulation on more than one core simultaneously I get the same problems
reported in the previous paragraph.

I have not found any reports of problems with Linux (ubuntu or other)
running on Nehalem workstations.  Are there known problems that I have
overlooked?  Is there anything I can do to get a clearer picture of the
problem?

Roger