Firefox 4 no longer shows a Reload and Stop button on the Navigation Toolbar, but has a button on the right end of location that shows the different states. During the page load process it shows as a Stop button and after the loading has finished the button is changed to a Reload button. If you type in the location bar then that button becomes a Go button.
You can middle-click that button to duplicate the current tab to a new tab.

To restore the Firefox 3 appearance you can use these steps:

• Open the "View > Toolbars > Customize" window to move the Stop and Reload button out of the location bar.
• Move the Reload and Stop buttons to their previous position at the left side of the location bar.
• Set the order to "Reload - Stop" to get a combined "Reload/Stop" button.
• Set the order to "Stop - Reload" or separate them otherwise to get two distinct buttons.

I know I've gone thru that process already, but just tried again and the problem is.............the "Stop" and "Reload" icons do not appear in the "Customize" window....................