The scene is a simple room with a portal in the window, a daylight system with Corona sun in it, and Corona Sky in the environment slot.
Sometimes these black dots appear which don’t go away no matter how many passes I wait. Then, when I re-render the scene they are gone. Then appear again.
Also, for some reason they turned out white when I saved the image. So I made a scheenshot to show how they looked.
Build 2014/01/16
I think it had something to do with Arch&Design material in the scene. When I replaced it with Corona material, the problem was solved.
Can you upload the scene (the one with the arch&design materials)?
fixed
Sorry for reviving an old topic, but I am getting the same issue… Weirdly enough, my Xeon workstation renders everything clearly, but my i7 PC gives me the following results in the sequence:
Pretty sure I shouldn’t have any MR materials in my scene as all are fresh imports made for corona, but I’ll double-check. Really weird!
This is on Corona 1.3
Can you send this scene to our support? https://coronarenderer.freshdesk.com/support/tickets/new
Will do when I have some spare time later today! Need to get a job out the door first 
Hi, Maru!
I sorted it out! Seems like the issue was that I created the file on my Xeon workstation with Corona 1.3 and then offloaded it to render on a network PC that had an older Corona version (1.2.1)… I’ve updated the PC to 1.3 and it works fine now 
Sounds plausible.
Btw I remember similar issues with displacement and Siger plugins.
