Well, I'd spent a long time on my theme when I developed it a while ago, much of this was on the JavaScript for hiding/showing menus using different effects. Let me tell you, it's not as easy as it should be. I persevered partly to learn about more 'tricky' JavaScript.

Recently, for different reasons, I've been looking at the JavaScript libraries prototype and script.aculo.us. And I love them. There are other libraries about but you've got to settle on one (well, two in this case as script.aculo.us uses prototype) eventually.

Anyway, the upshot is that the dynamic menu behaviour on this site is now handled by these libraries and not my own JavaScript. It's fixed some of the general problems (e.g. can't type in to the search field) and some of the problems in IE (e.g. not all the menu was displayed). There are still some issues with IE (e.g. some text/styling disappears) that I need to look in to, but as I rarely use IE for my site I guess these will be low priority (sorry, IE users).