Hmmm, you're using one of the site cacheing plugins? Those things prevent dynamic data (like updated signature counts) from displaying their current state by design.
Generally though, they do allow dynamic pages (rather than pages from the cache) to display to logged-in administrators, -- giving a false impression of how your site visitors actually see your site. I'm guessing that you are logged in to your site on the Firefox browser, but that on IE and Chrome you haven't actually logged in.
If that's the case and you prefer to display live (rather than cached) data to your users, you should probably remove the cacheing plugin.