Some error in the Password Manger add-on for Firefox means that everytime the browser opens, it gives the annoying message that the add-on cannot be registered with Chrome.

The solution is to edit one of the files in the add-on, to support this higher version of Firefox.

I have done this fix, and have provided the file to download here, as although there was an abundance of instructions on how to fix it, no-one seems to have provided the file anywhere!

Hope this helps someone out.