Red-white Checker-box Tile Errors with Mountains

[Creepers99]

I'm sorry to flood the forums with error questions regarding mods, but I'm trying to create my first scenario and civ 5 is fighting against me to the last breathe. Now these red-white checker-boxes appear wherever I place mountain tiles in World Builder. I think this happened once before, but with hills, and I never got around to fixing that (that project was abandoned by me). If anyone knows if there's anything I can do to fix this, or if there is something I should download to fix this, I'm willing to listen. I appreciate any replies