Did you try going though safe mode? I had to do that to get it to work properly on my computer. Safe mode will essentialy stop all other programs from running, which means you get a lot more direct access to the files themselves. Safe mode should also always be entered as admin, so that should not be an issue either.
It's a bit more of a complicated aproach, but if you can't get it to work like the other suggestion then this might be a solution for you.