Please keep the discuss@mpich mailing list cc'ed. Yes, this is a problem. Is one of your machines actually a 32-bit machine or did you just install a 32-bit OS on a 64-bit machine? If it's the latter, you could reinstall a 64-bit OS. If you can't do that, another option is to build MPICH in 32-bit mode on both machines by passing CFLAGS=-m32 to configure on the 64-bit machine. This will require that you have the right 32-bit libraries installed on your 64-bit machine (such as the 32-bit libc library). This option is typically for expert users, and is not a recommended option for most users. -- Pavan On 12/01/2012 09:34 AM US Central Time, D Griffiths wrote:

x86_64 for the one, i686 for the other. I take it this is the problem?

Thanks for getting back to me so quickly.

-- Pavan Balaji http://www.mcs.anl.gov/~balaji