So I created a small mod in seyda neen, just next to the light house, using the common tavern exterior, then I made the interior cell, three stories tall, in a rough approximation of the layout the outside has. I've populated the lowest(basemant story) with three npcs, some forges, alch equipment, etc. That's it. I went to test it in MW, and as soon as I enter the cell(second/ground level) the game crashes, both when I manually enter the cell by activating the door and by using the coc command. I haven't edited any scripts, nor created any. The few items that I've changed, I've changed the ID to create a new item, and I've only done this to clothing, and maybe three weapons.

I'm really not sure what's going on here, but it has me dismayed.
-morrowind is patched with MCP 2.0, I don't have any other mods running at the same time, and I've tried it with a fresh toon each time. There's only one entry in the warnings.txt file:

Model Load Error: Meshes\o\LootBag.NIF cannot load file in Meshes\o\LootBag.NIF. will use the default object Marker_Error.NIF

Loot Bag error? I assume that's the Overfloow Loot Bag - an item which appears when too many items (about 1024 on PC, 256 on Xbox) are in one cell. You mention that you placed only a handful of objects, so maybe something got, well, multiplied somehow?

Could you upload the .esp file somewhere? We could check that if it's a problem in the mod itself, or if it's your game malfunctioning.

I did duplicate quite a bit of clutter, so this is probably the reason. Is there any way too fix this? I really don't want to have to create two new cells for each floor.

I know it's not the game, it's a fresh install, patched up with a fresh version of MCP.

I'll see if I can't upload it, my internet is being snarky.

Sounds to me like you have a missing mesh, based on that error report. I don't know about Morrowind, but Oblivion will crash if you try to load a cell with a missing mesh. Missing textures will look odd but will still load, but missing meshes will typically crash the game.

You say you made some new items, I would make sure you have properly done that and not inadvertantly created an item without a mesh. That error is telling you that the game is trying to load an item called "LootBag" and looking in the folder "Meshes\o\" for a mesh for LootBag but cannot find it. I'd bet dollars to donuts that is why your game is crashing.

Now you need to figure out what LootBag is and why the mesh is missing and how to either put the proper mesh in that folder or stop the game from trying to load LootBag.

If it is indeed the Overflow Loot Bag, then I am at a loss as to how you could have inadvertantly deleted the mesh for the Overflow Loot Bag.

When I say new items, I mean I just changed the ID to create one, and then changed the stats a little bit, keeping keeping the original mesh/texture. I didn't create any new meshes/textures. I'm usually very careful about changing items, I usually create every item with the prefix 1A so that after I'm done creating something I can check it without having to scroll through everything.
Also, usually when a mesh fails too load, the game will tell you. I had a bad mesh change for the imperial broadsword, and it came up with an error, but the sword still loaded into the game, just with a white blade.
I too would be baffled at how I could have deleted an essential mesh

Hmm. Well, the error is saying "cannot load file in Meshes\o\LootBag.NIF"

If you look in Morrowind\Data\Meshes\o\ is there a .nif file there called LootBag.NIF? If so, then I wonder why the game cannot load it?

Anyway, good luck, we have exhausted my knowledge of Morrowind modding here but hopefully Minimir will be able to help you out.