Modern versions of Windows 10 and 11 require all drivers to have a verified digital signature. If yours is revoked or unverified, you'll see a yellow exclamation mark in the Device Manager.
Before diving into complex fixes, confirm the issue is specifically the Virtual USB Multikey. mastercam virtual usb multikey not working
Select and enter the exact path to the driver, usually C:\Windows\System32\drivers\multikey.sys . Reboot your system to apply changes. 3. Resolve Driver Conflicts Virtual Usb Multikey Windows 10 Mastercam - Google Groups Modern versions of Windows 10 and 11 require
Run the installer as (right-click → Run as administrator). a clean uninstall may be necessary:
If the drivers remain broken, a clean uninstall may be necessary: