The first thing that seems wrong is that your using lowercase -x which DISABLES x11 forwarding. You need a capitol -X flag.
But, the error doesn't sound like its remote X windows related because it didn't complain about not being able to find the $DISPLAY environment variable.

You will need OpenGL setup (direct rendering) to run Pro/E. You should need to actually install opengl, but your X11 needs to be loading the "glx" module.

glxinfo | grep "direct rendering"

gives the status of direct rendering.. if it says "No". Pro/E won't work. Getting it to say "Yes" may take some work, , but the easiest way to make it work is to pickup a lower end Nvidia card and install the retricted drivers Ubuntu will prompt you about.