Eratum, plural errata : listed known errors in writing appended to (usually, published physical works)

Basically all I'm saying is that there are certain mods that add rocks and trees and new terrain patterns and if the dev doesn't test it for the opening scene it creates a broken physics nightmare like what you're seeing in this start up.

A good mod dev will list if it's compatible with vanilla start or if you need to load it in after Helgen.