Of course, then it kept doing it. It's not that it crashes very often, and that it crashes at all is partially a by-product of the software being both memory leaky and my tendency to leave browsers open for days, if not weeks, on end, if I can. But every time 1.5 has crashed, it's wiped out what few new bookmarks I'd added in. At least, whenever I find stability again, I can upload that August backup.
Today, I'm trying out Firebird 0.7.1. I don't know what known bugs there are for it. It doesn't use my Mozilla preferences, so I'm having to figure out what many of my passwords are. But at least it shouldn't wipe out my bookmarks.