Im using the theme Whitelight from WooThemes.com.
If I activate W3 Total Chace the lightbox doesn't work anymore.
Please have a look here:
Right now the plugin is not activated.
Feedback from WooThemes support:
It's possible it's loading an old version of jQuery, or loading it incorrectly - this is the only thing I can think that would cause the lightbox script to fail.
Thanks a lot for your help!