parabellum I had exactly the same problem. I managed to cure mine by doing the following.
open the following page;
www.dslreports.com/drtcp
and download the file;
DRTCP021.exe.
If you cant open this web page, then you need to use a friends pc and save the above file on a memory stick then transfer it to yours.
Open up the exe file to a small grey window called DR TCP.
the bottom window has the title ADAPTER SETTINGS with an MTU field next to it.
In the MTU field insert 1392 for every connection listed in the ADAPTER SETTINGS.
Restart the pc. Every web site should be available to you know. Start enjoying the free porn the WWW provides!!!
let me know how you get on
DB