You site is down right now, so I can't check it out, but I think I've got a pretty solid idea of what's going on.
Reason that Firefox squashes the image and Internet Explorer doesn't: When I wrote Kubrick, I decided to add max-width, a CSS property, which IE doesn't support, but which makes life easier for users of 'modern browsers'.
The reason I did this, was a preemptive strike of sorts. I use it on my own site as well.
It has caused a bit of confusion with people who don't know CSS all that well, which is of course unfortunate. For this reason I'll reconsider its inclusion in the future.
Regardless of this, you should never post images that are large than the width of the column in which they reside (in Kubrick's case 450px), unless you know what you're doing. In variably it'll end up causing you layout problems.
My best suggestion, if you aren't interested in resizing your images, is to bring up a calculator and add style="width: 450px; height: xxxpx;", in which xxx is the calculated height of the image.
It won't look too good though, as most browsers suck at resizing images without making them look grainy.