Why am i getting an error which says "Derivative input XX at time XX is Inf or NaN.Stopping simulation. There may be a singularity in the solution.If not, try reducing the step size."

I am modelling a SAR ADC with a capacitor array. At the start of simulation, the voltage at the top of the capacitor array is shooting up to very high values and simulation is not proceeding.At the start of simulation, the array is in reset state and there are no voltages connected to the capacitors. I am not sure if this is the reason for the voltage spike .The capacitor initial voltage is set to zero, but the node voltages are not initialised. I notice that this problem happens at very low cap values below 1uF. Can someone tell me why this is happening and how this problem can be solved? Is there a way to initialise node voltages in Simulink?

Details of the connection: There are a number of capacitors connected in parallel.Voltages are forced at the top and bottom of the capacitor through switches.But all these switches are off at the start of simulation, so that there is nothing connected to either edges of the cap at the start of simulation when this problem happens.