Redesign the homepage to have a look at alternative skin. Get rid of shedding light. What happens?
Depending on the length of page, background still moves, which is causing issues. There's also the readability aspect. We've adjusted and adjusted and adjusted, and are still hearing some issues.
Please think about an alternative solution, maybe a quick mockup if you have an idea Solution should work over the background images, behind the header/subheader/lead text