Automatic creation of users I have a big problem. I don't know why, but every day are created users in my site. It's not a normal registration because I have disabled the block for login/registration in my site. The users' status is locked and they are many.

What can I do?
Disabling block is pointless. You need to truly disable registration itself. Go to Administration » Configuration » People and under Who can register accounts? select Administrators only. If that's not enough, make sure you have all security updates installed.

Note: exact path to this setting may be a bit different in Drupal 6 or 8, but you should be able to find it easily enough.