(Some) images link to a page instead of to a lightbox

Hi, I successfully installed lightbox-2 on WP 3.0 beta1 and it works fine…mostly. But on this page, for example, the first two images operate as a lightbox, the second two jump to a display on a page (not even a blank one).

http://69.89.31.227/~arzanaor/arti-e-mestieri/squerariolimaestri-dascia/la-famiglia-casal/

Was it something I said? 😉