Weird url passing what does it mean, am I hacked?

I noticed yesterday that sometimes I was seeing a strange url passing at the bottom of the browser when clicking around my site I'm working on while watching the page loads, its calling to mouserunner.com and I went to the site and it is a bunch of links, my site is on a private server for a large media company, clues on what this means and where to look to stop it, what's it doing scraping my site or something? Thanks folks...