I'm using ruby-mode.el with GNU Emacs 20.7.1.
When I attempt to use the tab key to fix the indention of my Ruby source
code, Emacs crashes.
My .emacs file is quite simple. I've included it below.
Any idea what could be causing this?

(custom-set-faces)

(setq load-path (cons (expand-file-name "~/emacs/") load-path))

;; Turn on font lock mode for all modes which support it.
(global-font-lock-mode t)

(autoload 'ruby-mode "ruby-mode"
  "Mode for editing ruby source files")
(setq auto-mode-alist
      (append '(("\\.rb$" . ruby-mode)) auto-mode-alist))
(setq interpreter-mode-alist
      (append '(("ruby" . ruby-mode))
              interpreter-mode-alist))

(autoload 'run-ruby "inf-ruby"
  "Run an inferior Ruby process")
(autoload 'inf-ruby-keys "inf-ruby"
  "Set local key defs for inf-ruby in ruby-mode")
(add-hook 'ruby-mode-hook
          '(lambda ()
             (inf-ruby-keys)
             ))
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