Hi,
I have just found this post after having the same issue, however it is an easy fix, rather than re-applying your theme, go to editor and look at your header.php file, look for:
<!–[if lt IE]>
<script type=”text/javascript” src=”<?php bloginfo(‘stylesheet_directory’); ?>/ie_png.js”></script>
Change the <!–[if lt IE]> to <!–[if lt IE 7]>
Update your file and all should be good.
Cheers
Lee
