Corner Chat Screen Overlay Issue

Hi

I am using the Chat plugin on a Genesis theme installation. The child theme I am using called Serenity has a large central slider across the homepage, the URL is http://www.greenwichmums.com.

My issue is that whenever I activate the plugin and set it to operate from the corner it is overlaying across this visible page, apart from the slider image. I've attached a screenshot to better explain what I mean.

So far I have disabled all plugins (apart from your dev update one) and it is still occuring - so it looks to me like its a clash with the theme itself. Can you help me with this please?

Incidentally I use the same plugin on a different genesis driven site with no issues at all!

Thanks

James.