It's not adding an input of type submit that breaks this behavior, it's that you named the INPUT "submit". When you have a DOM node reference to a FORM tag, its submit property is usually a function that submits the form. When you create a form field or button whose name is "submit", then you overwrite the default submit function of the FORM with a node reference to the form field or button. It's best to not name form fields "submit", "title", "elements" or "name", as those are important properties of the FORM object.
Related reading: JavaScript, DOM, and the Humble FORM.
