as I said last time, you have a member variable with the same name as the class:

private JFrame PasswordBox;

this is a bad idea anyway. You don't actually use this variable, so just delete
the above line. In actionPerformed() you could replace this:

PasswordBox.setVisible(false);
PasswordBox.dispose();

with this:
this.setVisible(false);
this.dispose();

Which at least makes the window disappear when you enter the correct username &
password though it leaves the program running with no way of quiting it,
depending on the OS you are using.