Silgrad Tower from the Ashes

After I work in the heightmap editor, save my progress, then try to save my esp, I get this error message:
Error saving land height data for cell (insert coordinates) Error correction attempted.

Every cell that was edited by the heightmap gets that error message, but landscape data shows up fine in the CS and ingame, any idea whats wrong?

did you generate LOD textures? don't know why, but that usualy clears it up for me.

Just save it and reload. That usually clears up the problem. You may have to do one quick sweep of the land to make sure that the game didn't mess anything up in the save (which can usually be fixed).

Thanks for the help guys, it still happens occasionally, but its not to bad, my next question, this is really starting to bug me: The CS crashes whenever I tell it to show overlay, I named the overlay correctly, and I've been in the area of the overlay, what is wrong?

I don't know, I've got the same problem so I'd like to know too.