First of all: Why do you refer to two different versions of gallerific.css? I see versions 3 and 6, the former overwriting the latter.
But the most interesting part is that IE does not interpret "position: absolute" correctly for div.loader. Looking at IE developer tools I can see that POSITION for div.loader is all upper case, maybe this is the issue? Firefox converts it into lower case in CSS view and interprets it correctly ...