Singularity problem in Simulink

I am designing a power system in Simulink, and keep getting this error message:

"Derivative input 1 of 'firstordersmlrev2/powergui/EquivalentModel1/State-Space' at time 0 is Inf or NaN. Stopping simulation. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances)."

I have tried using different solvers, reducing the tolerances, reducing the step size. The powergui block is highlighted when the error message is displayed. I am using a continuous ideal switch.

[Roger Stafford]

You should consider the possibility that you do actually have a singularity in that derivative which the message referred to, and if so, take the necessary steps to alter your design so as to correct that. Apparently Simulink is unable to handle it as it is.