I have an old Asp classic CMS application that powers several websites. It uses modal dialogs and only works in Internet Explorer. Now they don't work anymore in IE8. What is the cause?
It should still work if your users either add your site to the list of trusted sites, or else set Protected Mode to OFF.
They apparently changed the security settings for showModalDialog in the interest of conforming to the standards, which is ironic because there is no public standard for showModalDialog.