I'm having problems configuring the column view in a particular file  - I can't insert/add a column.  

I can navigate around it, and S-M-<left> works fine, but S-M-<right> brings up the message "Wrong type argument: integer-or-marker-p, nil"

In a newly created test file S-M-<right> worked fine - prompts for a property. I don't know if it's relevant but in the problematic file, when I use C-c C-x C-c to create the column view, no #+COLUMNS line appears.

Any ideas how to troubleshoot it?

Gez (beginner, GNU Emacs 23.2.1, Org-mode version 7.01trans)