Ponti wrote:I´m just wondering why the hell I can´t access a chess site with my IP ...

It's a simple thing. One IP of a Internet Service Provider is shared by several users (usually a number between 100 and 1000)
Some of these users have viruses (or are hackers!) and they target some sites linked, for example, to Project Honeypot.
These sites think that the IP is a menace and they blacklist it, then any site using Project Honeypot for anti-spam/virus is suddenly unreachable by that specific IP address.
It's not because you're from Brazil, but simply because someone else using your Internet provider has viruses.