I'm not sure I'm seeing things as they really are. A design I'm working on displays in Chrome, IE, Safari and Opera just fine. But when I fire up FireFox and look, my slider is hanging off to the right?!
Firebug add-on for Firefox may help. Try installing it, then looking at the coding of your site slider within it. It lets you make changes to the site on-screen, and it may help you figure out what code block is causing that problem.