Well, I don't know precisely why it wasn't working, but I got around it by having PHP send a cache-control header, so the live example will no longer be useful. The mystery lives on :-)
This one has me stumped - I have a site with a simple search box in corner, which works perfectly fine. However, if you run a search and then click the Back button on IE8/9, then you can't highlight the text in the search box (and if you try, then you will lose the ability to even click in the box afterwards). This problem doesn't occur in Safari, Chrome, Firefox, or even IE7. No amount of google searching will bring an answer, so I hope someone here has run into this before!