It seems like you have covered most alleys here.
You say that you tried disabling all add-ons; I would like to suggest that you enable all add-ons by doing the following:
Start > Run (or
Windows + R)
This will start Word with all available add-ons active.
The reason I suggest this is because I encountered a similar and very rare problem around six months ago; after some trial and error, I found that this was a good workaround.
In your case, you may wish to use this technique - assuming it works - until a permanent solution is found.
Please also remember to ensure that no instances of MS Word are running before going through steps 1-3. Furthermore, once you have opened MS Word via the
run command, ensure that you leave at least one instance of it running in order to work with other documents; otherwise, if you close all instances of MS Word, you will need to re-open it using steps 1-3 again.
I found that creating a shortcut on the desktop which performed steps 1-3 automatically resolved my problem as it was just a case of me having to double-click the icon in order to open MS Word with no errors. I even went to the trouble of using the MS Word icon for the shortcut, so there is virtually no difference and it is just as if you are opening MS Word as normal anyway.