Your computer must be set to boot on the optical drive/USB port first before defaulting to the internal hard disk drive. If that is not the case, you need to first modify the respective BIOS or UEFI setting, usually by pressing the Del key or the F2 key (or some other key combinations depending on your machine). Once in the BIOS/UEFI screen, find the boot menu or similar and set the order of the boot devices properly, with your optical drive/USB port in the first position. Save your changes and reboot your computer. Insert the Salix CD/DVD or USB key, and start up your computer.