Open Command Prompt as Administrator and run: bcdedit /set testsigning on
Changes to the way Windows handles the USB stack meant that the original MultiKey source code would trigger a Blue Screen of Death (BSOD) or simply fail to start (Error 39 or Error 52). What is "MultiKey 1803 Patched"? multikey 1803 patched
Use the Device Manager to "Add legacy hardware" and point it to the patched .inf file. Open Command Prompt as Administrator and run: bcdedit