I am running Algor Sim 2011 x64 edition and I get the same as what you described as well. I also have large memory and disk space. I ran small models successfully and then ran progressively larger models until FW does not start at all.
I hope the development team answers this question for us.
I am using Simulation Mechanical 2012 and the fatigue wizard still works on a small model with 80000 DOF but will not run at all on a larger model with 154000 DOF. The models are both using linear static analysis results with similar settings - the only difference is the mesh is all tets in the larger model.
I get a "runtime error 6 - overflow" message".
Has anybody found a workaround for this issue???