Marcelo de Moraes Serpa wrote:
>GNU Emacs 23.2.1 (x86_64-apple-darwin, NS apple-appkit-1038.29) of 2010-05-08.

>Backtrace attached.

Thanks.  It looks like a problem with calendar.el: Org tries to use a
function in the calendar-buffer named "*Calendar*" and fails because
there is no window that contains such a buffer.

 - are there any customizations starting with "calendar-" in place?

 - can you open the calendar using M-x calendar RET?

 - if you can open the calendar, what is the name of the calendar
   buffer?

   To find out the name of the calendar buffer use this simple
   function:

   (defun dmj/print-buffer-name ()
     "Print name of current buffer."
     (interactive)
     (print (buffer-name)))

   Simply place cursor after this expression and evaluate it (C-x
   C-e).  After this you can M-x dmj/print-buffer-name RET to display
   the (internal) name of the calendar buffer.

Best,
  -- David

--
OpenPGP... 0x99ADB83B5A4478E6
Jabber.... dmjena@jabber.org
Email..... dmaus@ictsoc.de