Till now my guess is that it's related to the kids corner. So I'd bet rolling back to Windows 8.0 will only help if you will be able to clean your kid corner.
If I'm right, a hard reset without restoring the backup should also do the trick.
If you'll do the downgrade anyway, would you report back if it works and what you did? I'm especially interested in the settings restore process. Will it work, will you use it?
Thanks and GOOD LUCK if you decide to go this way!
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