I have a Ubuntu 12.04 on my Laptop and have the problem that since a few weeks I can't reach some Websites while others work fine.
I'm sure that the Problem must be somewhere in my System, because in the Windows (**same** Laptop) everything works.

When I'm trying to reach one of those Sites I get redirected to the o2-search which tells me that the site couldn't be found.
One of the sites which doesn't work is <http://www.putpat.tv> if this helps you.