[jQuery] [FORM] Plugin -Error after Upgrading to jQuery1.3

After upgrading to jQuery 1.3 the FORM plugin has an issue with FILE
uploads. When attempting to submit a form containing a file input
type using .ajaxForm() it throws an alert stating: Error: Form
elements must not be named "submit".
Here is the form:
<form id="imgUpdate" action="#" method="post" enctype="multipart/form-
data">
<input type="file" name="mainImage" id="mainImage" />
<input type="button" name="imgCancel" id="imgCancel"
value="cancel" />
<input type="submit" name="imgUpdated" id="imgUpdated"
value="update" />
</form>
And the jQuery:
var optionsI = {
target: '#imgStatus',
    beforeSubmit: imgSwap,
    success: showResponse3,
    url: 'save.php',
     type: 'post'
};
$('#imgUpdate').ajaxForm(optionsI);