Hello Faba :)
This is  an example of images renered on PC: http://www.renderosity.com/mod/gallery/index.php?image_id=2041867&user_id=34800&np&np
and on the Mac : http://www.renderosity.com/mod/gallery/index.php?image_id=2033745&user_id=34800&np&np
Technicaly, there is no difference except the "tiles" problem.

I just sent a bug repport to Daz...
Wait and see.

 
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Holyforest,
Hundreds of shaders for Carrara