Dell Optiplex 755 Windows 10 Pro live-usb Error

[Ralf Mardorf]

On Thu, 14 Jul 2016 19:29:11 -0500, Robert Crawford wrote:
>My Dell tower has booted from live-usb, now it won't. I get this error
>"Selected boot device not available".
>
>My Dell has 8gb ram, 128gb Samsung SSD Boot Drive, WD 1td data drive.
>
>I've checked the usb device settings in the bios everthing is set to
>"On".
>
>When I press F12 for boot menu, I select usb device and get above
>error with on option is either F1 to try again or F2 to go into bios
>settings.
>
>I create live-usb with this tower. I can boot with one of my laptops
>(2 run Windows 10 pro, 1 runs Ubuntu 16.04).

A shot in the dark. Have you ensured a real shutdown of Windows 10, by
pressing the SHIFT key + clicking on shutdown? AFAIK by default Windows
10 doesn't make a real shutdown. I guess it's not related to your
issue, however, you never knbow.

Most likely related is the EFI issue.

You mentioned "BIOS". I'm confused. AFAIK Windows 10 requires U/EFI. I
suspect simply booting from an USB device could be impossible, resp.
requires UEFI/secure boot things and some machines might only allow to
boot from DVD and HDD.

I didn't read this link myself, but noticed that somebody explained the
EFI thing:
http://askubuntu.com/questions/328906/ubuntu-bootable-usb-not-at-all-detected