We use Google custom search in the header of every support page: http://nimb.ws/T7tOsE
But you might not be able to see it if you have some sort of Ad Blocker plugin in your browser. Could you try disabling it if so, or search our forum using a different browser?
Thanks for posting the screenshot. I wonder if you might be able to do me a favour? Would you mind privately emailing me a screenshot of your Firefox addons page?
You can send it to support@[thisdomain.com]
You can access the Firefox addons page by entering this in your browser: about:addons
I will then install all of them in my Firefox until I find one that blocks the Google Custom Search on this forum.