(deleted by moderator - see /kb/forum-rules-and-guidelines )

A possible cause is security software (firewall,anti-virus) that blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program.

Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process and the updater process.

See:

• https://support.mozilla.org/kb/Server+not+found
• https://support.mozilla.org/kb/Firewalls

Hello ! Thank you for for your answer, but unfortunately this did not solve anything. Concerning your first link, it does load websites, but it is just terribly slow (take me one full minute for a very simple website while it takes only 2 seconds on another browser) but anyway even adding firefox in firewall permissions did not help :/

The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information. Note: This will cause you to lose any Extensions, Open websites, and some Preferences.

To Reset Firefox do the following:

1. Go to Firefox > Help > Troubleshooting Information.
2. Click the "Reset Firefox" button.
3. Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish.
4. Firefox will open with all factory defaults applied.

Further information can be found in the Refresh Firefox - reset add-ons and settings article.

Did this fix your problems? Please report back to us!

I already did this too before, but except loosing my persona it did not change anything :(

Thank you anyway !

Try to boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that helps.

It works fine in safe mode , does it help for any solution ? :/

If it works better in Windows Safe mode then a possible cause is still your security software.

Did you try to remove all rules for Firefox and the plugin-container process from the permissions list in the firewall?

If you did then did you your firewall ask again for permission?

I removed the rules for firefox and put it in permission list again, it did not change anything. I also added the plugin container file, but again no change, still toooooo slow.

still no solution to give me ? :(

I just installed version 17.0b6 over the top of version 18 and am now back up to speed. You can download older versions of Firefox via the Support tab.

Now I just can't close Firefox or it will install 18 again....

I have the same problem ! For me, the solution was to remove the extension: BROWSER PROTECT. This extension was installed without I know it and without my consent and action !!!

I hope this solve your problem too !

Thank you for your help, but I don't have this extension installed on firefox :/

Are you sure, you don't have this extension !? I discover it by accident, because this extension doesn't appear in the extension list of Firefox !!! I saw it in the /start/programs menu of Windows. And there is a folder "Browser Protect" in /Documents And Settings/All users/Application Data.

Couldn't find anything like that.

Thank you for your help. I have to forget mozilla and welcome another browser...

I had the same problem and am using FF 16 and refuse to update to 18.