From Tunngle Wiki
- The encryption connection could not be established because cryptographic libraries weren't loaded properly
- You have a Broken Security Suite Problem.
This might result from the corruption of your operating system.
If Tunngle was working before try to restore to an older Windows System Restore Point.
If the problem persists try to uninstall Tunngle, reboot, go to Start->Run->%appdata% and delete the Tunngle folder that you find inside. Install Tunngle again and reboot.
Please also check our Broken Security Suites section.