Internet Explorer 7 returned an error in gallery_assist_lightboxes\js\gallery_assist.prettibox.selector.js
Message: Expected identifier, string or number
Line: 87
Char: 3
Code: 0

I applied the same kind of fix as you do for Fancybox some times ago (http://drupal.org/node/703732) by removing the "," in line 85.

Was:
overlay_gallery: myOverlayGallery, /* If set to true, a gallery will overlay the fullscreen image on mouse over */
});
});

Changed to:
overlay_gallery: myOverlayGallery /* If set to true, a gallery will overlay the fullscreen image on mouse over */
});
});
IE7 no longer returns an error after this fix. IE8 doesn't care and works fine with and withouth the fix, Firefox too.