Cycles + GPU + render layers = Renders become black after rendering

[McBuff]

I push my render button and it all starts of well. I can see the picture rendering in the render result window. I’m rendering out just a single one of my render layers.
When the render is done, my render turns black and every trace of the rendered image is gone.

In my compositing nodes I can see the node of my render layer and the preview actually takes on the aspect ratio of my rendered image, but it shows those blocks as if it was transparent.
Rendering to a png gives me the exact same result. A fully black image.

[poolo]

hi, i just fixed the same problem. when you display compositor for the first time your render layer is connected to the composite NODE. i was making some changes and istead of composite node a conneced everything into VIEWER NODE. and that is the reason why was my render turning black. you must have everything connected to composite NODE. at least thats how i fixed it . sorry for my english