It's not the red terrain that's the problem - that's just the mesh showing.  My problem is that dark flat box on the right - should also be a terrain mesh

Bruno, I can't check right now as I have a render going.   Something I started yesterday in 6 and I'm renndering it in 7 but I will check when it's done (that could be tonight or tomorrow morning 'pending on how long the render takes

Gill