"Unbalanced parentheses" error when using custom configuration file

[Dmitry Pankratov]

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In GNU Emacs 21.2.1 (i586-suse-linux, X toolkit, Xaw3d scroll bars)
 of 2002-09-11 on amdsimb
configured using `configure '--with-gcc' '--with-pop' '--with-system-malloc' 
'--prefix=/usr' '--exec-prefix=/usr' '--infodir=/usr/share/info' 
'--mandir=/usr/share/man' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' 
'--with-x' '--with-xpm' '--with-jpeg' '--with-tiff' '--with-gif' '--with-png' 
'--with-x-toolkit=lucid' '--x-includes=/usr/X11R6/include' 
'--x-libraries=/usr/X11R6/lib' 'i586-suse-linux' 'CC=gcc' 'CFLAGS=-O2 
-march=i586 -mcpu=i686 -fmessage-length=0 -pipe       
-DSYSTEM_PURESIZE_EXTRA=25000   -DSITELOAD_PURESIZE_EXTRA=10000         
-D_GNU_SOURCE ' 'LDFLAGS=-s' 'build_alias=i586-suse-linux' 
'host_alias=i586-suse-linux' 'target_alias=i586-suse-linux''
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: POSIX
  value of $LC_CTYPE: ru_RU.KOI8-R
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US
  locale-coding-system: cyrillic-koi8
  default-enable-multibyte-characters: t

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

In file .emacs: (setq custom-file "~/.gnu-emacs-custom")
1. start emacs
2. M-x toggle-debug-on-error
4. M-x c-mode
5. M-x menu-bar-options-save

==> debugger called

Debugger entered--Lisp error: (scan-error "Unbalanced parentheses" 1 690)
  scan-sexps(1 689)
  forward-sexp(689)
  custom-save-delete(custom-set-faces)
  custom-save-faces()
  custom-save-all()
  customize-save-variable(debug-on-error t)
  menu-bar-options-save()
* call-interactively(menu-bar-options-save)
  execute-extended-command(nil)
  call-interactively(execute-extended-command)

Notes:
1. the same error for c++-mode, pascal-mode.
2. no error for text-mode, lisp-mode, ada-mode.
3. after first save in text-mode, lisp-mode etc,  no error triggered in other 
modes

Recent input:
n - e r r o r RET ESC x c - m o d e RET ESC x m e n 
u - b a r - o p t i o n s - s a v e RET ESC O A C-@ 
ESC O B ESC O B ESC O B ESC O B ESC O B ESC O B ESC 
O B ESC O B ESC O B ESC O B ESC O B ESC w q ESC x r 
e p o r t - e m a c s - b u g RET

Recent messages:
.gnu-emacs-custom has auto save data; consider M-x recover-file
Loading places from ~/.emacs-places...
Loading places from /home/dmitry/.emacs-places...done
forward-sexp: 
Loading debug...done
Entering debugger...
 [2 times]
Mark set
Back to top level.
Loading emacsbug...done