Use the RESOLUTION soft key. Set it to HIGH for the final verification pass, but use STANDARD for quick checks. High resolution slows the simulation down significantly but shows surface finish issues.
Many operators confuse the graphic test with the full simulation. The iTNC 530 offers a program run, full-sequence simulation that checks not just the geometry, but the kinematics of your machine. symulator itnc 530
Do you use the iTNC 530? What is the worst crash you caught using the simulator? Let me know in the comments below. Use the RESOLUTION soft key