IE8 Object doesn't support this property or method Line: 1119 lightbox.js

As usual... IE has broken my Lightbox2 installation with this error showing:

Message: Object doesn't support this property or method
Line: 1119
Char: 5
Code: 0
URI: http://www.infiniteewebdesign.com/sites/all/modules/lightbox2/js/lightbo...

Drupal 6.16 multi-site
Site in question: http://www.infiniteewebdesign.com/
Click on "Client Login" (Lightbox Modal) to see error in action.

I have Googled and searched the Drupal DB without any info no this particular error so, anybody have any ideas?>

Ralph