is it:
google-analytics.com ?
if so, it's probably* DNS cache poisoning, which redirects you to ads and a bunch of annoying shit.
I have some links open on my home pc (for how to deal with this) as it's infected with this shit. I'll reply here later on with the links. You can google shit like:
"google-analytics redirect problem"
"how to get rid of google-analytics redirect"
And related search terms to see heaps of people having issues with it.