Thanks for the reply Phil.

I will let you know which files I am using. I am NOT using IH.

Meanwhile, I forgot to mention, I am having this problem with products with multiple images only. On a single image product, zoom functions perfectly.

Following is the page source HTML with multiple products:
HTML Code:
<!--bof Main Product Image -->
<div id="productMainImage" class="centeredContent back">
<script language="javascript" type="text/javascript"><!--
document.write('<a href="images/large/TestImages/IMG_0021_LRG.jpg" class="bonzer_zoom" rel="product_info">
	<img src="images/medium/TestImages/IMG_0021_MED.jpg" alt="test" title=" test " width="400" height="300" /></a>');
//--></script>


<noscript>
<a href="http://MyDomain.com/Folder/store1/index.php?main_page=popup_image&amp;pID=15" target="_blank">
	<img src="images/medium/TestImages/IMG_0021_MED.jpg" alt="test" title=" test " width="400" height="300" />
	<br /><span class="imgLink">larger image</span></a></noscript>
</div><!--eof Main Product Image-->
</div><!--EOF DIV Main Product Image-->

<div>&nbsp;</div>
<div><!--BOF DIV ADDITIONAL Product Image-->

<!--bof Additional Product Images -->
<div id="productAdditionalImages">

<div class="additionalImages centeredContent back" style="width:33%;">
      <a class="bonzer" href="javascript:void(0);" rel="{gallery: 'product_info', smallimage: 'images/TestImages/IMG_0021_1.jpg',largeimage: 'images/TestImages/IMG_0021_1.jpg'}">
	  <img src="images/TestImages/IMG_0021_1.jpg" alt="test" title=" test " width="100" height="75" /></a>
      <noscript><a href="http://MyDomain.com/Folder/store1/index.php?main_page=popup_image_additional&amp;pID=15&amp;pic=0&amp;products_image_large_additional=images/TestImages/IMG_0021_1.jpg" target="_blank">
	  <img src="images/TestImages/IMG_0021_1.jpg" alt="test" title=" test " width="100" height="75" /><br /><span class="imgLinkAdditional">larger image</span></a></noscript>
</div>
I have omitted HTML for images 2 and 3, to save space, but they look identical to small image 1.