I just noticed that the problem you were having, Kixum, also happens when I'm rendering a single image on a single computer and cancel it. When I start the render again in the same window (instead of a new window) without making any changes to the scene, I see different diffusion has been used. The edges of each rendered area don't match the original edges made by the previous render. It looks like the seed used to start the random numbering to create diffusion for a scene is not the same value for each render. So, of course, each computer node will have its own seed value to start its rendering of the scene when using multi-computers. Carrara Pro 4 needs the host computer to send the same seed value it's using to each node so they have the same calculations for global illumation before they start their renders. It would be better if Carrara didn't use a different seed each time the render button got pressed, as well. It needs a user setting that chooses to auto set/change seed values for a scene. So far, the best way to remove the checkerboard effect in renders is to turn on Interpolation Precision to 100%.

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