In catalog/product_info.php you have 2 pieces of code to be removed/changed.
Around about lines 27 -31
Delete the following:
CODE
<script language="javascript"><!--
function popupWindow(url) {
window.open(url,'popupWindow','toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,res
izable=yes,copyhistory=no,width=100,height=100,screenX=150,screenY=150,top=150,le
ft=150')
}
//--></script>
You also have this code around lines 108-113
CODE
<script language="javascript"><!--
document.write('<?php echo '<a href="java script:popupWindow(\\\'' . tep_href_link(FILENAME_POPUP_IMAGE, 'pID=' . $product_info['products_id']) . '\\\')">' . tep_image(DIR_WS_IMAGES . $product_info['products_image'], addslashes($product_info['products_name']), SMALL_IMAGE_WIDTH, SMALL_IMAGE_HEIGHT, 'hspace="5" vspace="5"') . '<br>' . TEXT_CLICK_TO_ENLARGE . '</a>'; ?>');
//--></script>
<noscript>
<?php echo '<a href="' . tep_href_link(DIR_WS_IMAGES . $product_info['products_image']) . '" target="_blank">' . tep_image(DIR_WS_IMAGES . $product_info['products_image'], $product_info['products_name'], SMALL_IMAGE_WIDTH, SMALL_IMAGE_HEIGHT, 'hspace="5" vspace="5"') . '<br>' . TEXT_CLICK_TO_ENLARGE . '</a>'; ?>
</noscript>
As the others have said above, you need to remove the javascript call.
Replace the whole section above with this
CODE
<?php echo tep_image(DIR_WS_IMAGES . $product_info['products_image'], $product_info['products_name'], SMALL_IMAGE_WIDTH, SMALL_IMAGE_HEIGHT, 'hspace="5" vspace="5"'); ?>