http://www.uesp.net/wiki/Morrowind:Vassir-Didanat_Ebony_Mine
While you can enter the mine, you cannot get close to the door due to strange invisible objects. This should be a relatively easy fix.
They are both related. In both cases, an object with Editor ID "OBTalonrockLg04" is causing the collision. It looks like it has a badly formed collision map, or it wasn't intended to go in a place like this. I don't know much about oblivion's engine so I am not really sure how to fix it in the model itself. I have had success with moving the rocks back and shrinking them a bit, but that is kind of a lousy fix. I have attached it anyway, it fixes both bugs.
The annoying part about this is that it looks great in the Construction set so you have no idea it's going to mess things up in-game.
OK fixed this one too, just rotated a rock a little to get its collision mesh out of the way of the entrance.
Fix merged with master file in version 050!
#1
interesting, there is a similar problem here: http://morroblivion.com/daraleth-ancestral-tomb-blocked-by-invisible-object