I am trying to install Ubuntu 13.04 ISO for AMD64 Athlon processor using USB drive (8GB). I did create a bootable USB using the USB installer from Win7 intel 32bit processor (followed steps from here: http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-windows). This USB is unable to boot on my AMD64 bit processor. The bios is able to detect the USB and once I change the boot order to USB and save exit from bios, I get a message saying "DISK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS CONTINUE" and unable to proceed further. However earlier to this I have successfully installed Ubuntu 13.04 on to my laptop which has Intel 32 bit core i5 processor with the same procedure but my desktop which has AMD64 is failing. I also tried to create the USB installer on my desktop which has the AMD64 bit processor and tried booting which also resulted in the same error. (My desktop currently has Win XP) Please help as I have run out of options. thanks, Nagarjun