Problem setting default font for my windows (frames)

[Ulrich Hobelmann]

In my init file I have the following definitions:

(set-default-font 
"-*-*-medium-r-normal-*-13-*-*-*-*-*-fontset-monaco13")

(defun font-monaco-13 ()
  (message "set-font")
  (set-frame-font 
"-*-*-medium-r-normal-*-13-*-*-*-*-*-fontset-monaco13"))

(setq after-make-frame-functions
      (append after-make-frame-functions
              (list (lambda (frame) (select-frame frame) (font-monaco-13)))))

The set-default-font, when I do C-x-e in the buffer, DOES change 
the font.  Likewise, when I call font-monaco-13, it DOES change 
the font.

But when I open a file in Emacs (by double-clicking in my system, 
which creates a new emacs window) it doesn't set the new font.  It 
seems like font-monaco-13 gets called (message appears), and the 
window changes its size, but then changes back again. 
after-make-frame-functions only contains my function.  Any ideas 
what is happening here?

--
XML is a prime example of retarded innovation.
        -- Erik Meijer and Peter Drayton, Microsoft Corporation