This may be old news, but Shadowbox v2 and IE8 -- will not work.
Force IE8 into IE7 emulation for now....
put this in /skin1/customer/home.tpl
AFTER:
<head>
INSERT:
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7" />
PS: There is a
beta of shadowbox3 --