Weird rings / circles with Iray light

Scene was too dim so I added an Iray spot light pointing at my one character.
Now in the renders I'm seeing these weird concentic rings / bands.It's like the light is projecting circles onto the scene or something.
Anyone know what causes this? I tried re-setting my render settings to default but they are still there.


Iray Projected Rings.jpg
786 x 823 - 587K
Comments
Did you try restarting Daz Studio? Sometimes memory corruption can cause weird effects.
Yes, thanks. It disappeard after a reboot.
I'm almost sad. It was kind of a neat effect!