So I have an old desktop and I am trying to bootup with Hirens BootCD via USB. Now it won't boot to USB, I've been into the bios and the told computer that USB has priority over all other devices. I've pressed F10 to choose which device I want and I select USB and it just sits there a with link flashing at me. I've tried with another USB and same result. I know that it isn't to do with USB's I've been able to use them.