Thank you both. I was thinking of using multiple ones for my user page, "Religious beliefs," "Political beliefs," etc, etc, which people could open if they cared to.
I've fixed it. The markup for a collapsible table that will be collapsed on load is:
Hi Nx! Could you walk us through how to do it without getting rid of that feature?
Fix basic functionality, lose one feature. It's not the end of the world.
Two features actually, you also broke RationalWiki:Collapsible Comment System, clicking on the links no longer uncollapses the box.