When creating a bootable Blancco CD/DVD, the provided ISO file(s) cannot be burned on CD/DVD by using the "dragging and dropping" method. The ISO files are image files and contain many smaller files. ISO files may also contain the hidden bootable elements that allow booting a computer from a CD/DVD. By default, In Windows 7, 8, Vista and 10, the easiest way to burn a CD/DVD from an ISO image, is to just double-click the ISO image file and use the Windows tool the process.
If you are using some CD/DVD burning software, then the correct way to burn the bootable Blancco CD/DVD is to use the "Burn Image to CD" function.
More information about CD image burning can be found for example from: