I have Toshiba Satellite C850-B798 with Windows 7 x64 installed.
I downloaded Ubuntu desktop x64 ISO and burn it to flash memory by universal installer, when I choose to boot from flash it give me nothing only black screen, I enter to BIOS to disable secure boot but I didn't find this option, also I didn't find UEFI or CSM.
I updated the BIOS to the last version 6.80 but nothing new happened, and I installed Ubuntu x86 but also the same results.
I installed win 8.1 x64 and I tried to find UEFI but I didn't find it.
I tried the ISO on vmware and it works well, also flash memory works well.
Simply, I tried all mentioned solutions but I still can't install Ubuntu, Why?
I also tried unetbootin, same results. There is no problem with boot order, and I installed win 8.1 by the same flash and same boot order and it worked fine