Maybe try downloading the F20 installer again?.......did you use Unetbootin to get the files on the USB?....

----- Reply message -----
From: "Leo Simmonds" <leo.simmonds@live.com>
To: "users@lists.fedoraproject.org" <users@lists.fedoraproject.org>
Subject: New Install
Date: Wed, Feb 12, 2014 11:10 am

Hi, I have v20 on a USB drive and want to install on a new machine with no OS currently in place.

When I boot, the Fedora install page comes up but then goes into "Starting Dracut Emergency Shell" after the "Warning: Can't mount root filesystem"

What now?