Horizontal Scroll Bar Has Stopped Working In FireFox???

Hi All
I recently installed google toolbar and enabled pagerank, autofill etc but now find there is no longer a horizontal scroll bar at the bottom of FF browser. This used to appear automatically if the window was reduced and now there is no sign of it.

I disengaged the navigation toolbar, bookmarks and google toolbar so that I had more screen so I thought that might have something to do with it, but when I activate them again the horizontal scrolling is still not active..!!

All I've done is swapped and changed things around so that everything i want appears at the top of my browser, page rank etc and fitted neatly at the top...

Does anyone know how to re-activate the scroll bar?

Cheers for any help
Andy