Hi
You could try installing and running Revo Uninstaller and see if it will get rid of Start 8 completely.
If you have already uninstalled it you will have to reinstall it and remove it using Revo.
http://www.revouninstaller.com/revo_uninstaller_free_download.html
If no one else has any other ideas, (I don't) maybe it's time to try and refresh your Windows 10 installation.
Just type Refresh in the search window and it will take you there.
You will have to reinstall any software that you have installed in Windows 10 after doing this but it will solve your .dll problem and it won't remove your files.
It would be a good idea to make a system image file when you get things working again.
I use EaseUS TODO backup and recovery...