Problem 1: UI Components of Nx Witness Client are accessible but all attempts to log in are being dropped.
Most likely it's the side effect of some antivirus or anti-malware blocking interaction between the Nx Witness Client and Nx Witness Media Servers. They're communicating via proprietary protocol that is usually considered to be suspicious by most of antivirus programs. Try to add Nx Witness software to the "allowed" list of your anitivirus.
If it doesn't help try to disable/uninstall those programs to be able to use Nx Software.
Problem 2: Many UI components are missing or client is closed right after start.
If you see missing notification bar, resource tree and login dialog it's most likely happening because your videoadapter doesn't match necessary software requirements.
- Minimal requirement is that videoadapter should support OpenGL2.1.
To check which version you have now just go here. Download and install OpenGL viewer for your platform. Run it and in resulting report you'll get the version.
If you see that you match minimal requirement first try to update your videodriver.
- !Note! Please use official web-site of your video adapter's manufacturer, not embedded windows update mechanism.