I login, and then, when I try to make a search or entering in a subforum,, the site consider me as non logged, presenting at the topo right the button "login"
Hello sarcastic user, this is not a common problem with other users so it is most likely your own browser setup that is causing this hiccup. In general, before posting, you should test with multiple browsers (Firefox, Opera, Chrome) and make sure that your browser accepts cookies and scripts.