If your connected USB device is showing up as unrecognized device and Delfi Communication Center tells you “USB Client validation error, please make sure that the client is activated” and “An error occurred while validating client”.

/ How to solve the “USB Client Validation Error” in Delfi Com Center

1. Hold down Windows button, and the R on your keyboard (Win+R).

2. Type control printers into the textbox in the Run window.

3. Right-click on the unrecognized device.

4. Click Remove Device in the dropdown menu.

5. Now Cold-boot your device and re-dock the device.
Check this link for most common cold-boot solutions https://support.delfi.com/support/solutions 
Look for the documents called <Terminal> - Boot options.

6. After following these steps above the problem should have been fixed.

If the problem is still present then try it again once more and make sure that is has been done correctly.
If it still fails to work try to call our support on +45 78 768 555 or write to Teknik@delfi.com