Download ubuntu, then download yumi and create a multiboot USB, set the priority of the bios, but every time I reboot does not start installing Linux, I do not know what could be wrong? or am I doing wrong? but I can not install the operating system with Windows 8.1
features
ASUS PC motherboard Hibrit CFX CPU phenon IIX6 1090T, video Gigabyte GT 240 1Gb, 4 GB of RAM
It is the first time I install ubuntu, as I fix it?