I'm grasping at straws, but are you sure that the previous version actually converged? Is it possible that the algorithm iterated many times and then gave you the values from the last iteration? Do you have the SAS log from before?
When you start from the "final" parameter values, the procedure will iterate only if it thinks it can further maximize the log-likelihood (minimize -2LL). If you display the iteration history, do you see the AIC/BIC/SBC/etc values changing in the appropriate directions? If so, then the previous "final" parameters were not actually optimal.
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