Ad appearing below Header Menu in 3.4.2

Hi,
I have just set up a site with the latest WordPress version 3.4.2 and am using the Thesis theme. I use Firefox as my browser. Now my site is displaying an ad bar below the header menu. I haven’t been able to track down where I can get rid of this yet so was wondering if anyone has any tips? I have no ad plug-ins installed

I see there was a thread already posted on this question but it is now Resolved. The person just posted they had resolved it themselves and it was a rouge Chrome extension making the ads appear, the post were not helpful to me.

I am very new at all of this so can you help me out by explaining what is making this ad show up and how I can get rid of it? Is it only showing up for me or will it be on there when my customers view my website? This site is for a business and I do not want any ads on it.
https://www.propertymanagement-auckland.co.nz

Thanks so much.