I use an altered form of the Septim Mansion mod, one where I added a bunch of cells to it. I used it for some time, but now want to take it off. After I uncheck it in Wrye Bash and play again, Oblivion crashes whenevery I try to save. I can only save my game with the mod active. Is there anything I can do to stop this from happening? I have already rebuilt my bashed patch without the mod in it. I even tried deleting the cells that I added to it, but when I do this, Oblivion won't even load. I guess what I did to change it caused this mod to totally hijack my game.

Are you quite sure that the cells you edited were within the mod and not part of the world proper? Try rebuilding your patch with the un-altered mod and then save. If it works, then you remove the mod, rebuild patch, load the save and make a new one. And if that doesn't work, how long exactly is 'used it for some time'. Any chance you can go back to a save prior to the mod?

No, all the cells that are modified begin with "00" in their ID so as not to confuse them with vanilla cells.
I have an old save from before I put this altered mod on, so I activated it and saved this old game with it on. Then I deactivated the mod on that save to see if the same problem would happen. My test showed that the old save still worked perfectly after I took the suspcious mod off. Therefore, maybe it's not the mod that hijacked the save, but something I did with the mod during my gameplay in my normal saves. So this brings up a new question.
I have left items on display in the cells that I added to this mod. Since my character dropped them, they would become persistent references in these cells. Would leaving persistent references in these cells cause my game to crash upon saving when I deactivate these cells from my LO?
Please note that Septim Mansion is an excellent mod and my problems with it come solely from my own doing.

Provided that the items in question didn't come from the mod, you should be fine. Pick up your items, then rebuild patch with the original mod and make a new save. If memory serves, the items will simply lose their reference until a new one is given (drop them someplace else).

This seems to be the problem, but I don't know what it means. Whenever I take off the mod and try to save my game without it, Oblivion crashes during the save. In Wrye Bash, the save shows up at a fraction of the size of the ones before it, about 6MB instead of 25MB.


Traceback (most recent call last):
File "C:\Bethesda\Oblivion\Mopy\basher.py", line 10841, in Execute
saveFile.load(SubProgress(progress,0,0.9))
File "C:\Bethesda\Oblivion\Mopy\bosh.py", line 5754, in load
self.tempEffects = ins.read(size)
OverflowError: long int too large to convert to int

So you saved a game with the unedited mod, then removed it (and rebuilt patch of course), and saving will now crash the game. I assume your character isn't inside the house when you remove the mod? This is the last thing I can think of for now. First, load a save with the mod, then in console type "coc testinghall", wait 3 full days, and then save. Now remove the mod, rebuild, and try to save the game. If it works, awesome. If not, go to Wrye Saves tab and right-click the save you made after waiting. Scroll down and choose 'remove bloat'. If after all this you still can't save a game w/out the mod, then I need to ask for some help on this one.

When I put the original mod back on, the game crashes on save. When I alter the altered mod, the game crashes on save. When the altered mod is activated and the same as it has been, the game is ok.
I've taken out all the items I put into the added cells, left the modded area, saved, deactivated the mod, played the save, tried to save again, crash.
I've removed the bloat quite a few times over the last weeks, and fixed the Abomb (because I've been having some slow FPS issues).
I''ve already tried waiting. My respawn time is set at 12 hours through Kuertee's auto time and save mod, but waiting after a respawn also does nothing.
I've also tried editing the mod through TES4Edit and the CS, taking the cells out that I added, but then Oblivion won't even start. That is really weird.
It is a puzzle, isn't it? I think I even stumped the Patriarch, Hey You. Very frustrating.

Did you try disabling the mod in the save itself, in the Wrye Bash saves tab?
Wrye Bash > Saves tab > select your save > right hand window disable the septim mansion mod

Hope that works for you