[jQuery] jQuery Form Plugin Problem: IE7 gives Object doesn't support property or method

[MeanStudios]

Greetings,

I'm using jQuery 1.3.2 and jQuery Form Plugin 2.25.
My code:
        $('#msre_file').change(function(){
                el = $(this);
                target = el.next();
                $('#entryform').ajaxSubmit({
                        url: '<?php echo $cp_url; ?>&ms_rel_file=upload',
                        type: 'post',
                        iframe: true,
                        success: function(response) {
                                el.attr('value', '');
                                target.append('<div class="msre_tmp_upload"
style="display:none;">'+response+'</div>');
                                target.children('.msre_tmp_upload').fadeIn();
                        }
                });
                return false;
        });

The form tag looks like:
<form action="index.php?C=edit&amp;M=new_entry" name="entryform"
id="entryform" method="post">

It works in FF2/3, Safari, IE8 but not in IE7.  I get an error on line
257 which is:
form.submit();

I've changed that line to document.entryform.submit(); just for kicks
and it still throws the error message.
I've also done window.document.getElementById('entryform').submit();
and it still doesn't work.
I've done alert(document.entryform.msre_file.value); and it gives me
the value of the file input correctly so I know it's referencing the
form correctly.
Yes I've changed the name attribute of the submit button to something
other than "submit".

I've also scrapped the jQuery Form Plugin and wrote my own form submit
function using the iframe method and it too worked in FF, Safari and
IE8 but still threw the same error in IE7.

I'm getting rather frustrated with this :(.

Any help would be hugely appreciated.