I've gone through a couple of primary browsers across a couple of different operating systems and operating system versions.
What's even more unfortunate is that I've had multiple backups where there were different changes to different versions of things. Fortunately I've been semi-active on keeping my links lists up-to-date, otherwise I might have bookmarks from 1998 in Neoplanet from back in my 16-bit Windows days.
Mind you, it's not so hard to import HTML links if they're accessible. My script-foo is good enough to deal with things. On that note, I do have some big links list text files I still need to process. Ignoring those lists, I was left with multiple sets of bookmark files from different eras, all of which may be valuable.
What am I to do? Well I installed Opera in order to import a couple of old Opera bookmark files (opera6.adr). I then imported them into Firefox. I decided on this double-step process just in case Opera needed to do some kind of funky change to the bookmarks file.
I then imported several Firefox bookmark files into Firefox.
I was left with countless thousands of bookmarks. Yes, thousands.. probably over five thousand.
This left me with two problems: Duplicate bookmarks and dead links.
CheckPlaces to the rescue..
Now I'm off to absorb a few huge lists of manually-kept links.