I have been going through the same problem ever since Firefox 8. It's very annoying and it has discouraged me from using my favourite browser. I don't understand the logic: why do I have to check and reinstall my addons each time I reboot my PC and open Firefox? If this is not a Firefox bug, please give me a hand in solving this issue. Thank you.

See:

• http://kb.mozillazine.org/Preferences_not_saved
• https://support.mozilla.com/kb/Preferences+are+not+saved

Make sure that you do not have security software that restores files on reboot to protect them against changes.

Troubleshooting attempts:

• Disabled firewall and anti-virus
• Uninstalled all add-ons
• Deleted prefs.js, sessionstore.js, and user.js

After computer reboots, firefox still keeps all the add-ons disabled, and I must enable each one manually.

I found a solution for my browser. In the about:config, I had to edit one of the preferences, "extensions.autoDisableScopes". I changed the value from 15 to 14.

I found the solution in this forum: http://forums.mozillazine.org/viewtopic.php?f=23&t=2320715

And also referenced this site: https://developer.mozilla.org/en/Installing_extensions

{edit:} My anti-virus detected a virus a few hours after these changes. This makes internet security more vulnerable.

tempbast, the solution you found has worked for me, too. Thank you for posting it.

See also:

• Bug 693743 – 3rd party add-on check doesn't disable those add-ons on start-up, if they were installed into the profile or application folder

Hello sicuta, I have to warn you, although it may be a coincidence, I got a virus a few hours after changing these preferences. So I'm guessing changing those settings is giving Firefox too much freedom, and making security vulnerable.

I recommend revert the changes, unless you understand understand the scope settings. I will downgrade my Firefox to an old version to use the add-ons.

My add-ons are installed in this directory: C:\Users\James\AppData\Roaming\Mozilla\Firefox\Profiles\iq9yzy2c.default

How can I change the add-on install folder if this not the permanent one?

I recently changed my PC's anti-virus and firewall from BitDefender to Avast. Now, I no longer have this problem. I don't know how, but I assume BitDefender conflicted with the add-ons. It's not enough to just deactivate BitDefender's active anti-virus scanner and firewall, you must go into safe mode and un-check BitDefender services from booting up on start-up. I'm sorry that it's a not a well tested solution.

Hello Tempbast, you seem to have hit the spot. Bitdefender was my antivirus too. So I have just turned to another protection system and after reinstalling Firefox 9.0.1 everything is OK. Thank you again.

If files are restored if Windows is booted then that usually means that some virtualization or other process is used to restore those files. If your anti-virus software has a forum or a page with FAQ then you can try to check if you can disable such a feature.

Yes, (anti-virus) Bitdefender was the problem for Firefox ver. 8 and 9. But it wasn't a problem for the earlier versions. So I'm more interested in Firefox's changes that made it's add-on's conflict with Bitdefender.