title: "cannot open display" error in Ubuntu using VirtualBox
body: <p>I installed Ubuntu (13.10) on a Virtulabox/VM running in Windows 8 and am getting errors whenever I try to run a gui program via the terminal:</p>
  
  <blockquote>
    <p>(google-chrome:13377): Gtk-WARNING **: cannot open display:
    127.0.0.1:10.0</p>
  </blockquote>
  
  <p>A similar error is displayed when I try to run firefox via the terminal.</p>
  
  <p>I have tried numerous attempts to fix this (setting $DISPLAY variable, installing X11, running as root, etc.) and nothing has worked.</p>