intermittent errors when using viper

This bug report will be sent to the XEmacs Development Team, not to your local site managers!! Please write in English, because the XEmacs maintainers do not have translators to read other languages for them. In XEmacs 21.2 (beta32) "Kastor & Polydeukes" [Lucid] (i686-pc-linux) of Fri Mar 24 2000 on blitz.inprise.com configured using `configure --with-modules --with-site-modules=yes --with-site-lisp=yes' Please describe exactly what actions triggered the bug and the precise symptoms of the bug: while using viper, i'll occassionally see an error message like this: ---- (138) (error/warning) Error in `post-command-hook' (setting hook to nil): (wrong-type-argument extent-live-p #<extent>) ---- a backtrace from a subsequent occurrence: Signaling: (wrong-type-argument extent-live-p #<destroyed extent>) viper-overlay-put(#<destroyed extent> face nil) viper-hide-replace-overlay() viper-change-state-to-vi() viper-mode() #<compiled-function (buf) "...(59)" [buf get-buffer buffer-name major-mode viper-vi-state-mode-list viper-current-state emacs-state viper-mode viper-emacs-state-mode-list viper-change-state-to-emacs viper-insert-state-mode-list insert-state viper-change-state-to-insert] 3>(#<buffer "*Article*">) mapcar(#<compiled-function (buf) "...(59)" [buf get-buffer buffer-name major-mode viper-vi-state-mode-list viper-current-state emacs-state viper-mode viper-emacs-state-mode-list viper-change-state-to-emacs viper-insert-state-mode-list insert-state viper-change-state-to-insert] 3> (#<buffer "*mail*"> #<buffer "xemacs-21.2＠ftp"> #<buffer "beta＠ftp"> #<buffer "*ftp ftp(a)ftp.xemacs.org*&quot;&gt; #<killed buffer> #<killed buffer> #<buffer "*Summary nnimap+mail:INBOX*"> #<buffer " *canonical address*"> #<buffer " *canonical address*"> #<buffer " *extract address components*"> #<buffer " *extract address components*"> #<buffer " *canonical address*"> #<buffer " *canonical address*"> #<buffer " *extract address components*"> #<buffer " *extract address components*"> #<buffer "*Article*"> #<buffer " *canonical address*"> #<buffer " *canonical address*"> #<buffer " *extract address components*"> #<buffer " *extract address components*"> #<buffer " *canonical address*"> #<buffer " *canonical a! ! ddress*"> #<buffer " *extract address components*"> #<buffer " *extract address components*"> #<buffer " *canonical address*"> #<buffer " *canonical address*"> #<buffer " *extract address components*"> #<buffer " *extract address components*"> #<buffer " *canonical address*"> #<buffer " *canonical address*"> #<buffer " *extract address components*"> #<buffer " *extract address components*"> #<buffer "*Article*"> #<buffer " *canonical address*"> #<buffer " *canonical address*"> #<buffer " *extract address components*"> #<buffer " *extract address components*"> #<buffer " *canonical address*"> #<buffer " *canonical address*"> #<buffer " *extract address components*"> #<buffer " *extract address components*"> #<buffer "*Article*"> #<buffer " *canonical address*"> #<buffer " *canonical address*"> #<buffer " *extract address components*"> #<buffer " *extract address components*"> #<buffer " *canonical address*"> #<buffer " *canonical address*"> #<buffer " *extract address component! ! s*"> #<buffer " *extract address components*"> #<buffer "*Article*">)) set-viper-state-in-major-mode() run-hooks(set-viper-state-in-major-mode) viper-post-command-sentinel() Recent keystrokes: x / t r a c e 2 TAB RET t r a c e 2 . c p p BS BS BS BS BS BS BS BS BS BS . . / t r a c e 2 . c p p RET C-x C-f / f t p ＠ f t p . x e a BS m a c s . o r g : / p u b / x e m a c s / b e t a RET C-s b e t a C-s C-s C-s C-g C-g M-> RET q q misc-user Recent messages (most recent first): Loading emacsbug...done Loading emacsbug... Reading directory /ftp＠ftp.xemacs.org:/pub/xemacs/beta/xemacs-21.2/...done Reading directory /ftp＠ftp.xemacs.org:/pub/xemacs/beta/xemacs-21.2/... Listing xemacs-21.2/...done Listing xemacs-21.2/... Quit: isearch Reading directory /ftp＠ftp.xemacs.org:/pub/xemacs/beta/...done Reading directory /ftp＠ftp.xemacs.org:/pub/xemacs/beta/... Loading dired...done ----------