Night-light Render Error

[joelyboy911]

Starting work on a new project, This plane and two others are exhibiting this error:



The two others are different shaped models but placed within the same lighting rig that consists simply of four target spots. It looks fine in the reader's preview mode, so I can't be sure if it isn't a graphical error on my computer. This is a standard-definition zoom 6 preview, but the dark notches appear on the plane in zoom 5 as well. Further zooms appear to be unaffected, but they are too small to notice it anyway.

If anyone knows what might be causing this error, my thanks in advance for your help.

[joelyboy911]

Well, I've confirmed that it isn't constrained to my PC, as the problem also displays on Adroman's machine.