Unfortunately, I also went through every"fix" I could find, as you have, and the only thing that finally cured the problem was the fresh install.
I used to see a new "fix" online with other users singing it's praises, but there were always some users that found that the fix did not work, I would try the fix and find myself in the second group
The only thing I can state that will solve this, in my experience, is the complete OS re-install which may not be practical for you at this time. The other thing is that I've found that this problem seems completely random with systems that look outwardly the same, as I've had other systems with similar software histories where this was not a problem.
As for the general edit of the registry keys when they are set with permissions so that you cannot edit them, they are normally critical keys and thus you must be careful in editing, sometimes you have to log in as the Hidden admin to achieve what you want, There is obviously some danger of trashing the system if you remove the wrong key. but If you back up your registry before any of these changes you can recover by use of the recovery console, although this is always an involved event
Only you can decide if the registry edit route is worth continued pursuing, or that the error is workable with, until your next re-install.
I wish you luck in whatever you decide and hope you find a workable solution, but I cannot provide the magic wand