PHP iFrame Form Fun > IE is directing users to a completely diff link than FF or any+

The short run-down of our problem is that We are using the below code to iframe an inventory search form (being styled with CSS) using PHP. Everything works great, except in IE the submit button redirects to a different baseURL.

<?
$content=file_get_contents("http://used-cars.kimberlyautomart.net/kimberlyautomart/quicksearch-price.asp?type=used");
$content = str_replace('<base href="http://used-cars.kimberlyautomart.net/kimberlyautomart/"><div id="isearch">', $codeBeforeHead.'</div>', $content);
echo $content;
?>

Code (markup):

As shown, the base href we need submitted is http://used-cars.kimberlyautomart.net/kimberlyautomart. IE uses http://dev.kimberlyautomart.net (where it's displayed) instead.

The long walkthrough of the problem we are having is if you go to http://dev.kimberlyautomart.net/ and you click the inventory search button in ANY browser except for IE it will work just fine and go to the proper page. If you click it in IE it forwards to a url on the same subdomain.

When you click on the inventory search button;

IE goes here: http://dev.kimberlyautomart.net/kimberlyautomart/browse/view_detailed/type_used/

All other browsers go here(which is the correct page):
http://used-cars.kimberlyautomart.net/kimberlyautomart/browse/view_detailed/type_used/

Any help or guidance is greatly appreciated!

 

Change:

<button id="search_tab"

Code (markup):

TO:

<button id="search_tab" name="search_tab"

Code (markup):

..and let us know if that has any effect ?