It is a virus. Clues? Well, google would not stick up a page from blocked-website.com, with adverts, telling you thatt you are not allowed to access a page. They would stick up the google one, or if it a government diverter you would have a government page up.
That website is owned by DIRECTI INTERNET SOLUTIONS PVT. LTD, a company in India. \
This will lead you onto this blog about scams;l
http://suckerswanted.blogspot.co ... e-software-ltd.html
So they have been around a while and are finding ways to sit on their arses and make money from people they do not know.
I would suggest you have this spyware in there somewhere and they are making money by people clicking the ads on the popup.
You can find fixes on line for it, usually tweaking a registry line whilst disconnected from the internet. Or, you can give the little pricks a call on one of the following numbers;
http://www.ratite.com/whois/whoi ... RNET+SOLUTIONS+PVT.
(Macs are pretty immune to spyware by the way hence not having a problem on there).