Error message:   " PCGLSS0139:Matrix is Singular or Indefinite***************** "

I am trying to do a nonlinear simulation in Solidworks using silicon rubber and I get this error message. Can anyone help me out here?  I believe there isn't any errors in my part but the simulation always stops at about 3% with the following error message :

"Solution failure in a Step>1, it could be due to:

The solution may be at a buckling or limit point, i.e.,

displacements grow large under constant forces. If so,

for force control or contact problems, this is the end

of solution (check out the response graphs).

The solver numerical difficulties:

1. Reduce the Singularity-elimination-factor (.5 or 0.)"  

What does it mean and how can I solve it. please and thanks. Any help will be greatly appreciated !

Jordan