Alright here is the problem. I have created a dungeon for Skyrim called Darkness Falls (not a reference to DAOC) and the entire dungeon works fine except for one major issue. If a player enters the dungeon and fights any mob and then turns around and leaves the dungeon. Upon reentering the dungeon all of the mobs in the dungeon will have been teleported to one room and are just standing there looking stupid. I apologize if this is a well known issue but i have been unable to resolve this issue on my own. Thanks

Did you place the navMesh? And did you find borders and finalize the navmesh?
That behavior is usually a missing or malfunctioning navmesh, especially if you are using a 'dirty save game'.

Its most likely the old Navmesh issue there is a thread floating around here about it, if your NavMesh works the first time through its most likely ok.

Though the teleporting actors in a bit worrying as the Nav problem usually just causes actors to lose their pathing not to fall under the world, so you probably do need to look at the NavMesh and make sure its tidy -> no loose verts flying off into oblivion or into walls, rocks, whatever... make sure the whole area is Navmeshed or actors will have pathing errors and take jumps into the abyss.

Generally if something looks off it probably is.

Thanks for the replies and checked the navmesh out just in case but it is fine; I hand drew the whole thing. The actors dont actually fall under the world they all teleport to one room in the dungeon and stand there. If you were to enter the room without attacking them they will continue to just stand there but if you attack one of them they will all come to life and proceed to chase you through the dungeon just fine. The real disturbing thing is that all of my actors in the dungeon spawn in as the player passes through a trigger before entering each room; which means that the actors aren't even generated when they teleport. Arghh this is a major issue for me since my dungeon is not ment to be completed in one sitting. Also what is a "dirty save game"? Thanks again for the input.

Dungeons not intended to do in one sitting? You must seriously underestimate most players.. why would I go out of a dungeon Ive not yet cleaned?

Perhaps you must leave to collect something needed progress further in the dungeon? There are a myriad of reasons for this, and it occurs many times in vanilla quests.

I have no doubt that there are some players that would complete it in one sitting but i intend on making this a very large dungeon with mulitple links to the outside world. I also intend on integrating it with the radial quest generation system so that it might send you down to kill certain bosses in certain rooms of the dungeon. None the less back to my bug question .

Bump

That would be a game that has had your mod 'saved in it'.
You must use a clean save game that has never had your mod activated when you saved it.

What you are describing happened in Fallout. And it had to do with Navmeshes breaking. Usually regenerating them would fix it. And make sure you use the optimization option to clean up a dirty navmesh. (and go back afterwards and readd some bits that were deleted that you really want)
Sometimes converting your ESP to an ESM would work too. But this is a new game so it may have different rules for fixing the problem.

If that means what I think it means, no there is no fixing it in Skyrim with that method I'm afraid.

Edit: Or maybe this is unrelated.