I'd like to install Ubuntu on my old desktop computer. I followed the Ubuntu tutorial to prepare a bootable USB drive with Rufus with the following settings: http://pc.cd/dJritalK. I configured the BIOS so the USB-HDD is booted first: http://pc.cd/T1GrtalK. However, when I start the desktop with the USB drive inserted, I get the message "DISK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS ENTER". Any idea how to fix this?