Errors after upgrading Firefox in Kubuntu

If you have changed from the default (repository) version of Firefox, to the newest version from Mozilla using Ubuntuzilla, you have to run the following command in order to activate the "Check for updates..." under the help menu:

sudo firefox

After updating, when you try to run firefox as a non-root user, you get the following error:

The bookmarks and history system will not be functional because one of Firefox's files is in use by another application. Some security software can cause this problem.

with a link to this page as a possible fix.

The information given does not fix the problem at all, but removes all your history and leaves the bookmarks inaccessible. The following will fix the problem:

cd /home/USER/.mozilla/firefox/
ls

In this listing will be a directory with the name XYZ.default, where XYZ is some random collection of letters and numbers.

cd XYZ.default
sudo chown USER *

will fix the problem (where USER is your login name).

This problem has only occurred since upgrading to v3.5 and subsequent releases.