Even with the best tools, things break. Here is the emergency repair guide.
5.1. Download and verify
5.2. Install
5.3. Launch and configure
5.4. Import libraries
If you are still on Kontakt 6, stop reading and go upgrade. Native Instruments finally listened. The new Browser in Kontakt 7 and 8 is the first-party "ultimate manager." Here is the definitive install process for making it work flawlessly. ultimate kontakt library manager install