IE, Lightbox JS and security popup over SSL connection

A security popup occurring only in IE, "This page contains both secure and nonsecure items. Do you want to display the nonsecure items?".

Solution: Change the following line in lightbox.css:

#prevLink, #nextLink{ width: 49%; height: 100%;
background-image: url(data:image/gif;base64,AAAA);
/* Trick IE into showing hover */ display: block; }

to the following:

#prevLink, #nextLink{ width: 49%; height: 100%;
background-image: url(../images/blank.gif);
/* Trick IE into showing hover */ display: block; }

Add blank.gif in images directory of lightbox library