I just updated org-mode to version 7.8.09 (release_7.8.09.199.g5e4cff.dirty), and now get the following error when I try to open any .org file:
Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil) org-babel-header-arg-expand() run-hook-with-args-until-success(org-babel-header-arg-expand) org-cycle((4)) org-set-startup-visibility() org-mode() set-auto-mode-0(org-mode nil) set-auto-mode() normal-mode(t) after-find-file(nil t) find-file-noselect-1(#<buffer work.org> "c:/Dropbox/org/work.org" nil nil "c:/Dropbox/org/work.org" ((16640 12 . 1731) (37630 . 48608))) find-file-noselect("c:/Dropbox/org/work.org" nil nil nil) find-file("c:/Dropbox/org/work.org") steve-ido-choose-from-recentf() call-interactively(steve-ido-choose-from-recentf nil nil)