On firefox 5, how do you get the URL of the Web page you're on to display in the URL field; is there an option setting or something?

When I open a new window in FireFox 5, the URL of the Web page I'm looking at doesn't get displayed in the URL field. The get-around (hack) that I have to use is to type some gibberish in the URL field, hit return, wait for it to go to the page that says there's no such Web page, and then hit the back button; that's the only way I've figured out how to get the URL to display in the URL field. This is a total productivity killer. There must be some option that I can set to get it to display the way Firefox and all other browsers have always displayed the URL in the field. What's that option setting?! Thanx.