|When Firefox recently upgraded to version 4 and quickly thereafter to version 5, there were many changes to the top toolbars.|
Sadly they were not necessarily an improvement.
On the right of the toolbar is a small tab that may have an option to help. Also clicking on the blank part of the toolbar can bring up some options.
Another problem is slowness and jamming. Try searching the firefox help for 'firefox jamming' and see how many users have been affected. To overcome, some have reverted to version 3.
Good Luck - Keep us posted.