Super DOF error - Black and light blue screen.

When I try to render with super dof, as soon as I click the render button my screen flickers with a black and light blue pattern, then freezes and stays on a screen which shows a light blue background, with a giant black “L” shaped object in the corner. It does this every time and I’ve tested it on multiple maps, multiple subjects, and multiple areas. What could be causing this? I’ve been searching for an hour now and I haven’t found anyone with my error.

Any help would be appreciated, thanks.

Specs?

Super DoF barely works, if ever.

I found out what it was, had to turn off multi-core rendering.

Thanks for the help, though.