Just two or three days ago, I surprisingly found my entities in the Fast Dial folder became empty. Later, The Xmarks icon set in the button right corner of the Firefox showed an error mark. I tried to update the Xmarks, but it just gave an unknown error message with nothing useful (to me). Knowing nothing to do, I chose one stupid approach: add the entities for the Fast Dial manually.
Why I was stupid? I didn't think about other possibilities. I even didn't think about looking for solutions on the internet!
Maybe I was just too tired after so many works. Today, I sat at the desk with the Firefox connected to the internet, and I think about searching the solution with Google immediately. Oh, there exists smart solution. What I needed to do is to login my Xmarks page and restore the old bookmarks.
Here is the solution: Xmarks, Fast Dial and Firefox 3.5
Step 1: Login into your Xmarks page, then my bookmarks -> Tools -> Explore and restore
Step 2: Delete the empty Fast Dial link in your bookmarks and let Xmarks "synchronize now". Note that you should download the bookmarks from the server, do NOT merge them.
I never know that the Xmarks keeps so many backups of one's bookmarks. That's a pretty consideration for users.
If you need to restore one of your old bookmarks, just click one of the radio button and then View it to see whether you've chosen the one you want.