I haven't the heart to tell debelgeast, anyone else up for it?
I guess I'm the only one here, so... First a history lesson.
Back in the days of dinosaurs when we played Morrowind (as well as early Oblivion) those data file checkboxes were all we had, and we used them to activate and inactivate our mods. Activation and inactivation should really not be confused with installation or uninstallation. When you install a mod, it's files are downloaded, unpacked, and placed in a folder where your game can find them and use them. this includes your .esp, but also things like meshes, textures, some scripts (depending on the game) and archives ... bsa files. After that is done, you have to activate your mod, that means checking the little box in data files in one way or another. Nowadays, we use things like Nexus Mod Manager or Wrye Bashe or Smash, and other similar tools that check and uncheck data files for us.
When you go to uninstall that mod, you can if you wish uncheck that little box, and all that really does is make the game not add that mod into the load order when you start up the game. All those files, like the textures, meshes, bsa files and so forth are still sitting there, they haven't been removed. What's worse though, is that scripts belonging to that mod that were running still remain in your save game files. these are called orphans, because in a sense they just sit and spin, with no way to accomplish their intended purpose. they are designed to reset variables, use functions, and a whole variety of things, but if the mod is not activated they just can't do it. Whatever they CAN do, they WILL, and that's where the corruption of your game comes from.
In your case, your smith has a book placed in his inventory that no longer exists. Your forge attempts to use the orphans it can see to do the jobe you want, but it just can't because things are missing. Imagine the golden gate bridge with 200 feet of it's span missing in the middle. CArs could conceivably go almost halfway across, but they couldn't get to the other side. So, some of them would turn around to back, while others would try to back up and a huge mess is the result.
What I'm saying is your solution does nothing at all if you've already deactivated the mods.