I cannot connect with Dreamweaver CS5

Interesting! Was that dialog box always there? Because it would have been REALLY useful if you had shown all FTP related information, not just the settings box (and assume that we can immediately spot the issue).

Funny, there is a topic with that exact title in my browser history:

Big surprise: it’s a wrong or corrupted password.

Could you try all the login/password related suggestions from this article?