I've tried three different USB sticks, all known good and one I've booted off before on this machine. I've used SARDU's FAT32 formatter as well as RMPrepUSB and followed directions. Nothing works; when I boot the machine and hit ESC to choose the boot device, selecting Removable Device, it tells me there is no bootable removable device. Looking on the USB stick I can see the /boot directory and what appears to be the appropriate files.
Using the x64 version of SARDU, 2.05