Andy M.
Certified Pretend Chef
I was able to copy my Favorites file to the bookmarks. It's awkward, but usable.
It just think it was really irresponsible to offer an upgrade that didn't fix what was wrong with the previous version.
I'm sorry to hear of your problems. That's a new one. I just upgraded to FF 5 on my SO's PC and my MAC with no problems. There may have been an underlying issue that caused your losing your bookmarks.