Jmvelasco modalbox appear down the page instead centered at IE8

JavaScript
1

Hello,

Sumeria Productions

When you click at Dj’s/producers, each element there (Imox Maya, Telekinetic, Shriniva, Basslion) should be opened inside a modalbox.

The rest of tested browsers are ok, but in IE8 (not tested IE7) the modalbox is displayed below the page instead centered overlaying the page.

Please, any suggestion to solve this ?

Thank in advance.