OPERA still displays errors on stripped down page

at one point, I had striped out the following:
<br class="clearfloat" />
I am not able to reproduce the issue with opera in the Power Gallery demo page:
index.php?gallery=6&theme=dark
Where the demo page is working correctly, it leads me to believe there is some conflicting CSS on your page that is causing power gallery to break, but the inconsistency of my testing is making it impossible to pinpoint the exact cause.

Thanks for being so thorough, Jason. I removed any extraneous code and I'm including the code for the stripped down page for you to look at and a link to the page. test.php
Sooo bizarre. Even with all that, I still get the same display errors and the Loading... loop.
<?php
error_reporting(E_ALL);
ini_set("display_errors", 1);
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
<style type="text/css">
<!--
body {
font: 100% Verdana, Arial, Helvetica, sans-serif;
background: #666666;
margin: 0; /* it's good practice to zero the margin and padding of the body element to account for differing browser defaults */
padding: 0;
text-align: center; /* this centers the container in IE 5* browsers. The text is then set to the left aligned default in the #container selector */
color: #000000;
}
.thrColLiqHdr #container {
width: 80%; /* this will create a container 80% of the browser width */
background: #FFFFFF;
margin: 0 auto auto auto; /* the auto margins (in conjunction with a width) center the page */
border: 1px solid #000000; /* this overrides the text-align: center on the body element. */
height: 750px;
}
.thrColLiqHdr #header {
background: #DDDDDD;
padding: 0 10px; /* this padding matches the left alignment of the elements in the divs that appear beneath it. If an image is used in the #header instead of text, you may want to remove the padding. */
}
.thrColLiqHdr #header h1 {
margin: 0; /* zeroing the margin of the last element in the #header div will avoid margin collapse - an unexplainable space between divs. If the div has a border around it, this is not necessary as that also avoids the margin collapse */
padding: 10px 0; /* using padding instead of margin will allow you to keep the element away from the edges of the div */
}
-->
</style>
<!--[if IE]>
<style type="text/css">
/* place css fixes for all versions of IE in this conditional comment */
.thrColLiqHdr #sidebar2, .thrColLiqHdr #sidebar1 { padding-top: 30px; }
.thrColLiqHdr #mainContent { zoom: 1; padding-top: 15px; }
/* the above proprietary zoom property gives IE the hasLayout it needs to avoid several bugs */
</style>
<![endif]--></head>
<body class="thrColLiqHdr">
<div id="container">
<div id="header">
<h1>Header</h1>
<!-- end #header --></div>
<div id="mainContent">
<h1 align="center">
<?php
$pg_id = '3';
$pg_theme = 'dark';
include('/home/content/g/s/b/gsbadmin1/html/PowerGallery100/galleries/ribbon_fullsize/index.php');
?>
<!-- end #mainContent -->
</h1>
</div>
<!-- This clearing element should immediately follow the #mainContent div in order to force the #container div to contain all child floats --><br class="clearfloat" />
<!-- end #container -->
</div>
</body>
</html>