Error in menu-bar-update-hook: (error Point before start of prope rties)

[Marshall, Simon]

I occasionally see this error in the minibuffer, after which it seems
menu-bar-update-hook is set to nil.  Normally, in my session, it would be:

(imenu-update-menubar msb-menu-bar-update-buffers)

This time, I think it was immediately following a paste in a C++ buffer with
Font Lock mode (and a whole lot of other things no doubt) turned on.

I'm guessing it's caused by imenu, but anyone else seen this or have a hint
that would help track it down?

This is with CVS as of July 17 + Martin Rudalics' mouse-autoselect-window
patch. 

In GNU Emacs 22.0.50.3 (sparc-sun-solaris2.8, Motif Version 2.1.0)
 of 2006-07-17 on perth
X server distributor `Hummingbird Ltd.', version 11.0.100015
configured using `configure
'--prefix=/rvcarma/marshals/software/slash/usr/local'
'--with-x-toolkit=motif' 'CFLAGS=-g''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: en_GB.ISO8859-1
  value of $LC_CTYPE: en_GB.ISO8859-1
  value of $LC_MESSAGES: C
  value of $LC_MONETARY: en_GB.ISO8859-1
  value of $LC_NUMERIC: en_GB.ISO8859-1
  value of $LC_TIME: en_GB.ISO8859-1
  value of $LANG: en_GB.ISO8859-1
  locale-coding-system: iso-8859-1
  default-enable-multibyte-characters: t

Major mode: Fundamental

Minor modes in effect:
  delete-selection-mode: t
  mouse-sel-mode: t
  msb-mode: t
  partial-completion-mode: t
  show-paren-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