Well I have sh404sef installed with the search engine friendly urls and the mod_rewrite activated I can't deactivate it because if I do it the whole site doesn't work I get 404 errors, anyway with those options activated the website works well, when I hover my mouse over the register link, in the status bar of the browser appears this url "http://localhost/Create-an-account.html" that is the same url of the joomla core registration page in fact if I click on it that page is displayed instead of the CB registration page.