I started having this problem a few days ago (Intrepid - compiz enabled).
I coincide with an ubuntu upgrade of firefox and the installation of extension "split browser".
uninstalling split browser seems to have solved the problem for now.
I'm not certain if I had the problem before the latest upgrade to firefox with the extension already installed, but I think it was working fine.
BTW if it can help anyone that cannot access the menu or resize buttons : keeping "alt" pressed while clicking with the mouse anywhere inside firefox allows you to move the window and place it so as to have access to the menu/buttons.
I started having this problem a few days ago (Intrepid - compiz enabled).
I coincide with an ubuntu upgrade of firefox and the installation of extension "split browser".
uninstalling split browser seems to have solved the problem for now.
I'm not certain if I had the problem before the latest upgrade to firefox with the extension already installed, but I think it was working fine.
BTW if it can help anyone that cannot access the menu or resize buttons : keeping "alt" pressed while clicking with the mouse anywhere inside firefox allows you to move the window and place it so as to have access to the menu/buttons.