I just realized my earlier post looks like someone who just doesn't know
where his profile folder is. Here's an updated post, since the problem
isn't just with bookmarks any more. I just created a new profile and
deleted the old one (told it not to erase the files, though). I replaced
all the cookie, password, and bookmark files in the new profile with the
ones from the old FF3 profile (which had previously been an FF1 and FF2
profile), including the file in the bookmark backup folder, but none of
these files are active in my browser: I can't see my bookmarks, and my
cookies/passwords aren't showing up when I go to my usual secure sites.
What else can I do? Here are the files I replaced: cookies.sqlite
places.sqlite, places.sqlite-journal, signons2.txt, key3.db, and
bookmarks-2008-07-23.json I used just a normal copy & paste, and made
sure they actually replaced the default files created by the new
profile: was I supposed to use some other process?

Storm wrote:
> I just realized my earlier post looks like someone who just doesn't know
> where his profile folder is. Here's an updated post, since the problem
> isn't just with bookmarks any more. I just created a new profile and
> deleted the old one (told it not to erase the files, though). I replaced
> all the cookie, password, and bookmark files in the new profile with the
> ones from the old FF3 profile (which had previously been an FF1 and FF2
> profile), including the file in the bookmark backup folder, but none of
> these files are active in my browser: I can't see my bookmarks, and my
> cookies/passwords aren't showing up when I go to my usual secure sites.
> What else can I do? Here are the files I replaced: cookies.sqlite
> places.sqlite, places.sqlite-journal, signons2.txt, key3.db, and
> bookmarks-2008-07-23.json I used just a normal copy & paste, and made
> sure they actually replaced the default files created by the new
> profile: was I supposed to use some other process?
Whoops: all of a sudden, everything started working after I figured out
that I had to add the Bookmarks sidebar via the View menu. Why FF3
would default to having that turned off with a new profile is beyond me:
It caused a lot of confusion and wasted a lot of time, making me think
the bookmarks weren't being recognized. Apparently, I had to reboot FF
more than once to activate my passwords and cookies, which just started
working. I also flushed the cache, but don't know if that was part of
the solution.