If Gizmo Client takes too long to startup (black desktop & no Splash Screen), check for the following culprits:

Services that take too long to start

Disable Gizmo client (INSTRUCTIONS) and restart the pc. As soon as Windows loads right click "My Computer" - Manage - Services & Applications - Services

Click on the Status column to sort services and scroll down until you find services "Starting"

Wait for the services to load (press F5 to refresh) and then double click the services and set their Startup Type to "Manual".

Restart client & check if windows work correctly with previous services disabled, then re-launch Gizmo client