This must be an error in Viper. In both Aquamacs and Emacs.app, I often get an error something like: Error in pre-command-hook: (error viper-event-key: Wrong type argument, eventp, "cochran.tex") Is anyone else seeing this? In .emacs, I have: (setq viper-mode t) (setq-default viper-ex-style-editing nil) (require 'viper) Any help would be appreciated.