Hello everyone, I was downgrading a laptop (Asus X540SA) from Windows 10 to Windows 7, but I ran into a problem with the installation. I plug the usb with the windows 7 iso file, but after that i get an error which is saying "A Required CD/DVD Drive Device Driver is Missing". I was thinking of updating the drivers of the laptop or booting it with a CD, but I am not sure what to do exactly. I would be very grateful, if someone could help me fix this problem.