Style switcher not working since 2.0.3 upgrade

I know that some people have had problems with WP themes since upgrading to 2.0.3, but I have a slightly different issue.

I run WP using my own layout (ie not a pre-built theme) and a style switcher made as per this article at A List Apart.

It has worked fine for a long time but since I upgraded to the latest version of WP it has mysteriously stopped working. When I try to change the theme using my drop down menu, nothing happens. I can change the colour scheme via Firefox’s menu but this doesn’t change the header graphic along with it.

Has an anyone experience similar problems? Can anyone help?

My site is at https://www.vaguely.org/blog
Header is at: https://vaguely.org/blog/header.inc
Footer is at: https://vaguely.org/blog/footer.inc