WordPress "Click to toggle" and several features not working

I have a Tumblr style micro-blog here http://minterest.co/ (powered by WP) and it was working fine.

But I recently noticed that I am not able to “Toggle” different widgets. I am not able to add links or pictures from WordPress dashboard. But however when I changed the theme to default one everything worked.

I’m using the theme called Casual (FREE) by http://www.obox-design.com//theme.cfm/theme/casual

So any help to resolve this issue?

Thanks!