It shouldn't be in a UAC controlled area, I am going to make another installation attempt today in a completely different area just to be sure. (For context it was never in my program files, near my program files or near the skyrim installation) Firefox always asks me, and I always point it towrds ncmhandler.exe, same error. Looked for that unblock checkbox, it was nowhere to be found. I am always on the latest official version, so 2.2.1 as of like august 1st