I am trying to do the Jagged Crown quest. I have talked to Legate Rikke and I have walked with her all the way to Korvanjund cave. She made her little speech and then we killed the bandits.

However, as soon as we enter the Korvanjund Ruins, we are faced with a massive mound. Everyone just stands there and stares at nothing. Then, whenever I go outside to Skyrim, and then back into the ruins, Legate Rikki and Hadvar had already gone solidly past through the mounds of wall and rock.

Is there any way to fix this? I really want to follow through with this quest and storyline. Any help and any response would be appreciated. I have heard people encountering similar situations but I haven't read any thing about fixing it.