The sniffer page confirms that my IE 5.5 installation is in fact an older version of XML. So that's the trouble.

I hate IE6 but I am afraid to downgrade on my work machine after installing it. On my home machine, I will not upgrade to IE6, however I will investigate options for upgrading my XML engine without changing the browser version.

Is the newer version of XML absolutely necessary for the functions you're trying to pull off? In my experience, it's always good to allow older browsers if at all possible. You get fewer questions like mine cropping up all the time.

Incidentally, I did some hand-editing of lines 24/25/26 in the default.xsl file and it now has the four buttons selecting correctly. I don't know if this is because the original file is out of order, or if my bad version of XML is the cause of it all. I will find out in a bit.