module named cairo, python-gtk

[Mark Grieveson <dg135@torfree.net>]

In some python applications, such as exfalso, or gdebi-gtk, I get an
error regarding there being no "module named cairo".  For example, 

mark@debian:~$ exfalso
Traceback (most recent call last):
  File "/usr/bin/exfalso", line 69, in <module>
    main(sys.argv)
  File "/usr/bin/exfalso", line 46, in main
    util.gtk_init()
  File "/usr/share/quodlibet/util/__init__.py", line 44, in gtk_init
    import gtk
  File "/var/lib/python-support/python2.5/gtk-2.0/gtk/__init__.py",
line 48, in <module> from gtk import _gtk
ImportError: No module named cairo

I reinstalled exfalso, which went by without a problem.  But still,
this issue remains.  There is a broken link, that
being /etc/alternatives/python-gtk, which may or may not have something
to do with it.  Other python applications, such as tovidgui, work
without a problem.  tovidgui is not a part of the official Lenny
distribution, though, but it does rely upon both python and gtk, I
think.

As always, all ideas are welcome.

Mark