Here is the screenshot of the situation.

If this occurred after an update, one of your extensions might not be fully compatible with Firefox 17, or your toolbar customization settings file might be corrupted.

(1) You can manage your extensions (check for updates, disable all nonessential ones) here:

orange Firefox button or classic Tools menu > Add-ons > Extensions category

(2) You can bypass a corrupted toolbar customizations settings file as follows:

Open your current Firefox settings (AKA Firefox profile) folder using

Help > Troubleshooting Information > "Show Folder" button

Switch back to Firefox and Exit

Pause while Firefox finishes its cleanup, then rename localstore.rdf to something like localstore.old

Restart Firefox. Any improvement?

The screenshot looks familiar from another thread, I think it was a conflicting add-on but I can't recall which one.

the delicious bookmarks addon caused it for some users - there is an update available for it now: https://addons.mozilla.org/en-US/firefox/addon/delicious-bookmarks/

I found the culprit. Delicious Extension by AVOS 2.3.1 caused the problem. I disabled that one.

I installed Delicious Bookmarks 2.3.4 by Yahoo! Inc., AVOS and it is working fine now.

Thank you very much!