Well, I updated a spare, slightly older, computer from FF2 to FF3.6 and it seems to have worked perfectly. I then set a system restore point and did the same on this machine and I lost all of my bookmarks exactly as I did the last time I tried it. I went into the FF3.6 help section and followed the instructions for restoring bookmarks lost while updating from FF2 to FF3.6 and...... it didn't work. I went back to my newly established system restore point and that didn't work. I went back to the last system restore point which had been created automatically in the normal course of events (which was for yesterday) and that didn't work either. So I've gone back to OldVersions.com and reinstalled FF2 and all has been restored as before.
Can PPRuNe "HELP, PLEASE" work better than FF help etc. has done?