Be honest, getting sick of me yet?

Okay, further to my earlier post, I've decided to implement sIFR into my new site. I've used this before, and have got the results needed already. However (bet you saw that one coming, right?) using sIFR on my h1's breaks my jQuery sliding menu.

I really can't explain what's happening, so here is a live demo:

All necessary code is referenced in the HEAD of the index page. As you can see from the demo, the welcome h1 is rendered in sIFR, as is the 'one' link in the navigation panel. When this link is clicked, sIFR is switched off on this particular header.

Can anyone please save me from going mad?!