Xfrog and Greyscalegorilla seamless floor

Hi

I was wondering if anyonecan help shed some light/advice for me. Was running a simple test on Xfrog tree with Greyscale gorilla's seamless floor. When I cast Greyscalegorilla's lighting on the tree and greyscalegorilla's seamless floor. there are artefacts from the tree that seems muddled up by seamless floor. I have uploaded the image where the artefact is seen.

The artefacts occurred only when seamless floor is present...