My internet signal comes via a DSL modem/router and a switch which feeds an old Windows XP and a newish Windows 7 computer.
On the Windows XP computer I have no issues.
On the Windows 7 computer, some domains work without problem as well, for example
http://www.google.com/reader/view/ or heise.de.
Others, like google.de do not work at all. It tries to connect for some time and then says "Server nicht gefunden" (Server not found).
At a third kind reproducably only a certain part of the information arrives.
An example is gizmodo.com. I guess some part of the info comes from one domain and another part from another one.
The issue is exactly the same on FireFox, IE and Chrome. I temporarily stopped AVG and Windows firewall and it did not help.
So I think that Windows itself is keeping some blacklist. Any ideas?