Binabik: You can export (save) your bookmarks in Firefox (and any browser)
I'm not sure exactly in the old version of firefox since I have 2.0 sitting here right now, but in 2.0, you go to Bookmarks, and choose orginize bookmarks - where then you can find a file, export to export your bookmarks. (Will export to a simple html file.) And then if you lose it again, you can import back in the bookmarks.
I've never lost my bookmarks - I just simple install the 2.0 version and it copied everything over to the new version.
(hide) If you don't want other users to know what you are doing you can change into cloak mode in Settings (paying members only). (pauloaguia) (show all tips)