printing with ps-print-buffer-with-faces results in error-message:
 Wrong type argument: number-char-or-marker-p, nil 
I couldn't reproduce this with 21.4.9 (Linux), and up to date packages. 
Could you provide more information about the file and your setup
(custom.el, init.el)?
Anyone else see this?
-- 
\/ille Skyttä
ville.skytta at 
xemacs.org