Strange problem with Vote-It-Up

Whenever a user clicks on my ‘like’ (vote) button beneath my pictures, all the posts below that picture disappear, and all the posts above it stay the same.

I’m using the vote-it-up plugin, and the only modification I’ve made to it is to change the ‘vote’ picture.

This only happens on certain browsers – Firefox 4.0 beta seems to understand it, but the earlier versions do not. I think Chrome is fine as well.

I’m drawing a blank here. Does anybody have a clue what it could be?

My site is https://www.youlaughyouwin.com if you want to check the problem out. Thanks in advance.