HALF of V-Ray rendering is showing up grainy

[saulsid]

Greetings:
I am having difficulties rendering lighting in an interior scene. The bottom half of the rendering is showing up grainy. See image link below. I know the graininess is related to the location of the lights, also rendering speed slows down when getting to the grainy part. Any ideas from anybody on how to remove the graininess?

Thanks!

---