Currently XenServer has a problem starting a new Ubuntu 14.04 image. There is a problem with one of the Python scripts it uses to start machines. This should be fixed by an update soon, but for now it’s a really easy fix to perform real quick. Thanks to http://virantha.com/2014/05/21/ubuntu-14-04-trusty-on-xenserver-62/ for the quick instructions.

vi /usr/lib/python2.4/site-packages/grub/GrubConf.py
if arg.strip() == "${saved_entry}": to say: if arg.strip() == "${saved_entry}" or arg.strip() == "\${next_entry}":