Rated 2 out of 5 stars
1) It was not writed backup of a lost session before I restart Firefox - so, not only the session was lost, but "bookmarks" of tabs too... So, I lost all latest tabs. May be the problem is memory leaks of Firefox, but you should alert if bookmarks was not saved.
2) There is the problem with encoding of non-english names (page titles) of bookmarks. I'm trying to change character encoding in FireFox & in IE to UTF-8, but it was not helping... We have a garbage instead of page titles in the names of bookmarks.