I have just stopped opera, loaded the file from my original laptop SSD drive, as the adaptor has just arrived (rather than the backup I used, made the day the laptop expired), restarted and checked the bookmarks again. Now, under 'other bookmarks' is a folder with my old laptop id which has the speed dial entries in. Must be a problem with the backup, as the one on the drive seems to work. Thanks for your help.
@adroman The Content-Length error is normal. The "failed to find string" errors are normal. "The Installer process did not complete successfully." error is too vague.