Comment 28 for bug 231472

Hello,
The problem happens when you use Firefox as a root user. This has happened to me twice. You can fix the problem by creating a new profile using the Profile Manager of Firefox. However you will loose extensions and bookmarks and all your settings. Instead I found a simpler way - the problem apparently is that the file "places.sqlite-journal" in your 'corupted' profile folder gets literally owned by root. That is the file owner is now root - so to solve this problem just run -

sudo chown <your_username> /home/<your_username>/.mozilla/firefox/<profilename>/places.sqlite-journal

That solved my problem - I am sure that that is the only file that gets affected by running Firefox 3 as root.