It is impossible for there to be a correlation between IE and Firefox in regards to pages appearing or not. That is not a browser issue. I suspect it is just coincidence – I’ve been wrong before though so feel free to disprove me!
There is an exclude option in the admin page which I think will do the job you are looking for. If you are still having issues with unpublished pages not appearing one browser over another, then send me a link and I’ll take a look.
I suspect your problem is caused by you being logged into your admin panel in IE, but not in Firefox. Log out of your admin panel in both browsers and then check if the page shows up. I assume you will find both browsers show identical page lists.