Photoslide problems in IE 8

When I visit my web under Internet Explorer 8, appears this error:

Notice: Undefined index: in /homepages/46/d217370064/htdocs/mario/2011/modules/mod_image_show_gk4/styles/gk_musicity/view.php on line 73

In Firefox 4 and Chrome works fine

My site:

http://mariopestano.com/2011/

How could I fix it?

Thank you

Do you have error reporting on in joomla global configuration ?