Hi sabathyus.
Thanks for your interest in our software 🙂
Based upon your error messages, it looks as though you may have deleted a tissue, cloth or bone from your scene.
If you send your scene to "support at zivadynamics dot com" we could take a look at it for you if you like.
When deleting simulation bodies, you need to use the option found in the Ziva menu.
(There are accessory nodes that need to be deleted in addition to the mesh. Our menu item will do this for you automatically)
The menu options can be found here:
Cheers!
-jj