I was able to get your circuit to simulate. I had to add a ground connection to the LM555CM and make a couple changes to the interactive simulation settings.
To find the settings open the Simulate menu and click Interactive simulation settings. I set the maximum timestep to 0.00125s and in the Custom analysis settings under the Analysis options tab, I changed the absolute error tolerance (ABSTOL) from 1e-12A to 1e-10A. These loosened tolerances should allow you to simulate the circuit.
I've attached your circuit containing the changes I've made including the saved simulation settings. Just run interactive analysis. Hope that is helpful for you.
Jeff
National Instruments