Just a quick guess, but did you set all of the options (i.e. Max Time,
Iterations, Precision, Tolerance, Convergence, etc.) in your macro so that
everything is the same on the other user's system?

Maybe the other user did some work on another project, and the options are
still set to values that require far more calculation time and/or
difficulty converging.

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Regards,
Bill Renaud