With IFORT 10.x the compiler defaulted to 64-bit at install, but there's a script that can be run to switch the compiler to 32-bit mode. 

You may want to double check to make sure that it's in 64-bit mode by executing "ifort -V"

Warner Yuen
Scientific Computing 
Consulting Engineer
Apple, Inc.
Tel: 408.718.2859

On Sep 12, 2009, at 4:37 AM, users-request@open-mpi.org wrote:

Message: 4
Date: Fri, 11 Sep 2009 15:35:34 -0700
From: Doug Reeder <dlr@rain.org>
Subject: Re: [OMPI users] OpenMPI on OS X - file is not of required
To: Open MPI Users <users@open-mpi.org>
Message-ID: <3FA2D621-D5C7-4579-94B7-8A0BFA040D3D@rain.org>
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Have you checked that ifort is creating 64 bit objects. If I remember  
correctly with 10.1 the default was to create 32 bit objects.

Doug Reeder