emacs hangs when executing M-x run-octave

[Alan Barnett]

I want to run octave from emacs as an inferior process. 
I'm running emacs 23.3.1 on Ubuntu 14.04.

My .emacs file contains the lines

(autoload 'octave-mode "octave-mod" nil t)
(setq auto-mode-alist
      (cons '("\\.m$" . octave-mode) auto-mode-alist))

(add-hook 'octave-mode-hook
          (lambda ()
            (abbrev-mode 1)
            (auto-fill-mode 1)
            (if (eq window-system 'x)
                (font-lock-mode 1))))

(autoload 'run-octave "octave-inf" nil t)

Octave is installed on my machine:

cavu{asb}118: which octave
/usr/bin/octave

Octave starts properly from the terminal:
cavu{asb}119: octave
GNU Octave, version 3.8.1
Copyright (C) 2014 John W. Eaton and others.
This is free software; see the source code for copying conditions.
There is ABSOLUTELY NO WARRANTY; not even for MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  For details, type 'warranty'.

Octave was configured for "x86_64-pc-linux-gnu".

Additional information about Octave is available at http://www.octave.org.

Please contribute if you find this software useful.
For more information, visit http://www.octave.org/get-involved.html

Read http://www.octave.org/bugs.html to learn how to submit bug reports.
For information about changes from previous versions, type 'news'.

octave:1>


When I run emacs and type

M-x run-octave

the cursor turns into a circle with a rotating dotted arc inside.  octave doesn't start, and emacs is unresponsive (I have to kill it from the command line.)

Any ideas?
Thanks.