This is only tangentially related, but the previous post reminded me that I'd long ago moved all Kontakt-related data files off the c: drive, and decided to have a look and make sure they're all gone. They weren't.
There were a bunch of leftover installation files there in hidden folders under \users\all users. Not huge files, but irritating when installers don't cleanup after themselves. To locate them, open a DOS window and type in Dir \users\all users\Kontakt* /s