In phpmyadmin, if the name of the database you are managing has an underscore (_), the "Create database" box is shown on the main phpmyadmin page. This should normally say "No privilages". In the create database box, the default is your database name, except that the underscore is replaced with a question mark. Perhaps this is part of the problem.
I have tested this, and mysql does not allow access to any of the other databases, or actually allow you to create a database.