Hi Osa,
If the "Forgot Password" button has the focus, and the user presses enter then it triggers that button.
There's no simple option to disable "Enter" on a button when it has the focus, so the best option might be to re-arange the window slightly.
You can also change the "When Accepted Set Focus On..." setting for the _password_ field, so if you "tab" from there it goes to say the radio "yes" field.
cheers
Bruce