In the function `org-move-to-column' when you call (remove '(org-filtered) buffer-invisibility-spec) it is quite possible that `buffer-invisibility-spec' is just `t'. This will error, because `remove' expects second argument to be a list.
This happens when opening Babel code blocks in a special editing buffer (thus <C-c '> will not be set for them). -------------------------------------------------------------------------------- (defun org-move-to-column (column &optional force buffer) "Move to column COLUMN. Pass COLUMN and FORCE to `move-to-column'. Pass BUFFER to the XEmacs version of `move-to-column'." (let ((buffer-invisibility-spec (if (eq t buffer-invisibility-spec) t (remove '(org-filtered) buffer-invisibility-spec)))) (if (featurep 'xemacs) (org-xemacs-without-invisibility (move-to-column column force buffer)) (move-to-column column force)))) -------------------------------------------------------------------------------- Seems to fix it. Best. Oleg