Awhile ago I used the basic Cosmos FEA program and while limited in what it would do, it was very stable.  Now with the costly Simulation Pro I seldom run even a simple FEA analysis without an error message.  Examples: No data base found - no load applied - etc.  Usually when closing SW there is yet another error message if I have run Simulation.  I don't have the fortitude to try a really complex FEA.