simulink powerGUI has singularity

Good morning, I am sing simulink to create a power system. I have numerous PID controllers and keep getting an error before my simulation runs telling me there is a singularity in the power GUI.

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)."

How can I go about troubleshooting this. I am really stumped

Thanks