Speed dial installs, but the icon is not displayed
I have used Speed Dial for a long time, both on my desktop machine and my laptop, and I really like it. Recently I got a new desktop and installed the latest version of Firefox on it. Everything seems to be working fine, but when I try to add Speed Dial it appears to install properly but the icon doesn't appear on the menu bar. I have tried several times and each time I am told Speed Dial will be installed after I restart Firefox. However, clicking the button restarts FF, but the icon never appears! What is going wrong, and how can I get Speed Dial to work for me, as it has always done?