If you evaluate '(start-process "foo" " foo" "ls" 10)' an error occurs since 10 is not of type sequence. Then if you try to quit emacs the same error occurs which makes it impossible to quit emacs without killing it. In GNU Emacs 24.0.92.1 (x86_64-unknown-linux-gnu, GTK+ Version 2.24.6) of 2011-12-04 on cddr Windowing system distributor `The X.Org Foundation', version 11.0.11004000 Important settings: value of $LC_ALL: nil value of $LC_COLLATE: en_US.UTF-8 value of $LC_CTYPE: en_US.UTF-8 value of $LC_MESSAGES: en_US.UTF-8 value of $LC_MONETARY: nil value of $LC_NUMERIC: nil value of $LC_TIME: nil value of $LANG: en_US.UTF-8 value of $XMODIFIERS: nil locale-coding-system: utf-8-unix default enable-multibyte-characters: t Major mode: Lisp Interaction Minor modes in effect: tooltip-mode: t mouse-wheel-mode: t tool-bar-mode: t menu-bar-mode: t file-name-shadow-mode: t global-font-lock-mode: t font-lock-mode: t blink-cursor-mode: t auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t line-number-mode: t transient-mark-mode: t Recent input: ( s t a r t - p r o c e s s SPC " f o o " SPC " SPC f o o " SPC " l s " SPC 1 0 ) C-x C-e q C-x C-c M-x r e p o r t - Recent messages: For information about GNU Emacs and the GNU system, type C-h C-a. Entering debugger... Back to top level. (No files need saving) list-processes--refresh: Wrong type argument: sequencep, 10 Load-path shadows: None found. Features: (shadow sort gnus-util mail-extr message format-spec rfc822 mml mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231 rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mailabbrev mail-utils gmm-utils mailheader emacsbug tabulated-list help-mode easymenu view debug time-date tooltip ediff-hook vc-hooks lisp-float-type mwheel x-win x-dnd tool-bar dnd fontset image fringe lisp-mode register page menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock font-lock syntax facemenu font-core frame cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean japanese hebrew greek romanian slovak czech european ethiopic indian cyrillic chinese case-table epa-hook jka-cmpr-hook help simple abbrev minibuffer loaddefs button faces cus-face files text-properties overlay sha1 md5 base64 format env code-pages mule custom widget hashtable-print-readable backquote make-network-process dbusbind dynamic-setting system-font-setting font-render-setting move-toolbar gtk x-toolkit x multi-tty emacs)