@cadfather said: it looks so weird that it doesn't seem a vray problem (at any rate i never experienced anything this bad, and when it fails, a restart or importing the model into a new empty file does the job). Hi CadFather You are right,it wasn´t a Vray problem ...In fact after my post I start a new sketchup file within the same open session, rendered it with the existing vray settings and magic..it works like a charm. Conclusion - It was a Sketchup problem Then I visit the book http://www.aidanchopra.com/book-info and made a complete new set-up of shadows and geo-positioning of model and after a few tweaks the model is back rendering without problems - see sample. Thanks for your input [image: CC7u_Stairs-Shadowsandwall-paintings.jpg]