[Plugin: Visual Form Builder] Submit button misplaced on IE8

Thanks for reading this far. I’ve got further info:

When I hack visual-form-builder.php, comment out as below (line 1869+):

<div style="display:none;">
<!--
	<li>
		<label for="vfb-spam">' . __( 'This box is for spam protection' , 'visual-form-builder') . ' - <strong>' . __( 'please leave it blank' , 'visual-form-builder') . '</strong>:</label>
		<div>
			<input name="vfb-spam" id="vfb-spam" size="20" />
		</div>
	</li>
-->
</div>

…the submit button returns to it’s proper position, though of course the superfluous input textbox no longer displays in IE8. I’m hacking my plugin for now, but would of course much prefer a real fix. I don’t see how my css could be causing this problem.
I like non-standard verification, but maybe it needs another look?