Problem Installing Aweber Lightbox Hover Form

I’m having a problem installing code for an Aweber lightbox (hover) subscription form. I was told to just paste the code into a generic “Text” box in my sidebar. When I do that the form does work just like it’s supposed to – the problem is something in the code throws the entire look of the blog off – it’s like part of the Dashboard is showing on the home page. I delete the code for the lightbox and all is back to normal . . . ?!

Just wondering if this could have to do with the latest update to 3.1? If anyone has any advice/suggestions really appreciate it.

Thanks,