Weird artifacts in scene

could be wrong but it looks like some kind of caustics. I had the same issue and found a wine glass was the problem. You may want to look at any glass material in the scene.

A dodgy material somewhere . Turn objects off in batches and re-render until it disappears.

Maybe its something which has to do with one object in the scene. It happened to me once. i had to hide all objects and then i was un-hiding them one after the other until i found the problematic object.

Hi Said, Check if all your materials are Vray Materials (Standard materials aren't so good with Vray) or if you have VrayLightMaterials with very high values. These are the 2 things that come to mind... It might be something else, but check these first. good luck!