<??> makes emacs to hang up

As reported here

 http://groups.google.com/group/gnu.emacs.bug/browse_thread/thread/beeb776bfb0d69a0/66bd3239fbf91b40?lnk=st&q=nxhtml+hangs#66bd3239fbf91b40

here is how to reproduce the bug:
 * M-x nxhtml-mumamo <RET>
 * type <??>
 * when typing last > emacs hangs with cpu 100%
 * if type <? ?> then all ok

Thanks if you fix this :)

nXhtml version 1.32, GNU Emacs 22.2.50.1 (i386-apple-darwin9.3.0,
Carbon Version 1.6.0)
of 2008-07-01 on seijiz.local

Major mode: nXhtml/nxhtml

Minor modes in effect:
 mlinks-mode: t
 outline-minor-mode: t
 cua-mode: t
 show-paren-mode: t
 nxhtml-minor-mode: t
 shell-dirtrack-mode: t
 mac-print-mode: t
 tooltip-mode: t
 mouse-wheel-mode: t
 menu-bar-mode: t
 file-name-shadow-mode: t
 global-font-lock-mode: t
 font-lock-mode: t
 blink-cursor-mode: t
 unify-8859-on-encoding-mode: t
 utf-translate-cjk-mode: t
 auto-compression-mode: t
 line-number-mode: t
 transient-mark-mode: t
 abbrev-mode: t
 hs-minor-mode: t



Recent messages:
Loading nxml-uchnm...done
Loading rng-nxml...done
Loading rng-cmpct...done
Loading rng-xsd...done
Using vacuous schema
Loading imenu...done
Loading /Users/phretor/emacs/lisp/nxml/related/php-mode.el (source)...done
Using vacuous schema
Unable to load color "PaleYellow" [2 times]
Loading /Users/phretor/emacs/lisp/nxml/nxhtml/nxhtml-bug.el
(source)...done


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