I have run into an interesting problem. A model (which is admittedly of low stability) that I used in class today ran on the Mac (with warnings, but reasonably close estimates) but not on the PC (non-invertible). Both are Intel processors, both running R 2.9.2 and OpenMx 0.2.2. The model is of simulated data with boundary constraints on residuals because variance explained is very high.
I attach the script and data as a test case for the limits of similarities between architectures.