Well what you can do is with the interface plugged in you can go to device manager and open the Universal Serial bus section and find the my dmx device (SIUDI 6C I believe. might also say "Low cost"). right click it and select properties and then select uninstall the driver. Let it uninstall but if it takes a few mins and it just hangs there then just unplug the interface.
Now reinstall the program without the interface plugged in and that should do it.
Sincerely,