You customize your Firefox browser, get it looking the way you want it, but everything is set back to the default settings the next time you open it up, what do you do? This is likely due to a corrupt localstore.rdf file. While it sounds bad, it is easy to fix, although all of your toolbar customized settings will need to be redone.
Export your bookmarks, they will be lost when the following steps are performed!
1. Click the Start button.
2. Select All Programs.
3. Select Mozilla Firefox and the select Mozilla Firefox (Safe Mode).
4. The Firefox Safe Mode dialog box will appear.
5. Check the Reset toolbars and controls.
6. Click Make Changes and Restart.
7. Redo your toolbar customizations.
Your Firefox browser should now remember your toolbar customizations. Import your bookmarks and customize your toolbar.