The Enlightenment E17 desktop window manager is very unstable when I use the packages supplied with the Ubuntu 12.04 release. I have installed the Enlightenment E16 window manager using a source tarball from this website and after installing the libimlib2-dev package I installed the source thusly.
./configure ; make ; make install
And then I had to add the starte16 command to my ~/.xsession file. I logged out of my KDE session and loaded the Enlightenment desktop. The E16 window manager is very stable and usable for your Ubuntu desktop. If you wish to run the E17 window manager, then you would be better served by downloading the Elive distribution or Bohdi Linux. Both of these distributions include the Enlightenment E17 window manager and are more stable than the Ubuntu 12.04 packages. The Enlightenment E16 window manager has been in development for a long time and is worth a try as an alternative to the comparatively bloated desktops like Gnome or KDE. You may download the source tarball from this page. http://packages.ubuntu.com/natty/e16 The source from here is what I used to build my Enlightenment desktop and it is guaranteed to work for you.