When you are inside of a portfolio item and click the top image to zoom in further the light box appears on the bottom of the page just out of view. When you try to scroll to the image it continues to push it down causing a never ending page.
Sorry for the late reply, I was out of town. I forgot to mention that I have already tried that. I only have one plugin installed (Acurax Social Media Widget) which I can leave disabled till this is resolved.