Some problems occurs when your Internet security program was set to trust the previous version of Firefox, but no longer recognizes your updated version as trusted. Now how to fix the problem: To allow Firefox to connect to the Internet again;

• Make sure your Internet security software is up-to-date (i.e. you are running the latest version).
• Remove Firefox from your program's list of trusted or recognized programs. For detailed instructions, see

Configure firewalls so that Firefox can access the Internet. {web link}

If there is still a problem, please describe what you do and what the program does.

FredMcD, thanks for your quick reply. It turns out that when I just re-installed an older version of Firefox (Ver. 24), everything works fine and I am able to open FF. But when I upgrade to later versions (e.g., 32), I cannot even open FF. I followed your suggestion and looked into Windows Firewall, and even when it is turned off, I cannot open the new version of Firefox. But with the old version, things are fine. By the way, my Internet security program is Trend Micro, and I even entered www.mozilla.org in the "exceptions" list of trustable websites, but that did not help with FF 32 either. Any ideas or suggestions?

As a general suggestion of something to try:

Clean Reinstall

This bypasses any "bad" files in Firefox's program folder:

(1) If needed, download a fresh installer for Firefox 32 from https://www.mozilla.org/firefox/all/ to a convenient location. (Scroll down to your preferred language.)

(2) Exit out of Firefox, if applicable.

(3) Rename the folder (64-bit Windows folder names)

C:\Program Files (x86)\Mozilla Firefox

to

C:\Program Files (x86)\OldFirefox

(4) Run the installer you downloaded in #1. It should automatically connect to your existing settings.

Does Firefox start and stay up?

Note: Some plugins may exist only in that OldFirefox folder. If something essential is missing, look in these folders:

• C:\Program Files (x86)\OldFirefox\Plugins
• C:\Program Files (x86)\OldFirefox\browser\plugins

Type about:preferences in the address bar and press Enter.

Select Advanced > Network. Look for Configure How Firefox Connects and press the Settings button. Check the settings.

jscher2000, thanks for your suggestion. I tried it, but did not work. Firefox would not run, and I am back to FF 24.0 which does work on my PC.

FredMcD, under the "Connection Settings" in FF 24.0 right now the selected choice is "Use system proxy settings." Should it be something different, and if so, which one? FYI, I tried switching it to "Auto-detect proxy settings for this network" and then tried to upgrade to 32.0, but that did not help either. So I am now back to 24.0.

Under Options > Advanced > Network, set it to No Proxy. IF you are not using a proxy.

FredMcD, thanks again for taking the time to help. I changed the "Connection Settings" to "No proxy," and then upgraded to FF 32.0, but it did not open up. So I am back to 24.0. If you have other ideas, I am willing to try it out so that I can upgrade to the latest FF version.

On a different Firefox topic, I imported my "Favorites" list from IE to FF, and I do see them when I go through the "Bookmarks" tab on the very top of the screen. Then under "View" tab, I have selected "Bookmarks Toolbar" which places a direct link called "From Internet Explorer" a couple of lines below the main toolbar (my idea is to save a few clicks if I want to go to my IE Favorites. However, when I click on that direct link, I only see 3 entries ("Customize links"; "Suggested sites" and "Web Slice gallery," but I do not see the many entries that should be there from my IE Favorites list. The strange thing is that until a few days ago I used to see all my IE Favorites when I clicked on this direct link! What should I do?

Did you check the proxy setting after you loaded the upgrade?

Bug Report 1031347 – Firefox Full Installer Changes User Settings

Is there a way for me to check the proxy setting in Firefox after the upgrade when the upgraded version will not even loan or open?

If there is still a problem, Start Firefox in Safe Mode {web link} While you are in safe mode;

Type about:preferences in the address bar and press enter

Select Advanced > General. Look for and turn off Use Hardware Acceleration.

Poke around safe web sites. Are there any problems?

Then restart.

Generally speaking, Firefox stores non-default preferences in a file named prefs.js in your Firefox profile folder (if you have multiple Firefox profiles, check the one that was updated most recently). They are listed alphabetically, so look for ones starting with

user_pref("network.proxy.

As a shortcut to get to that folder, you can paste this into the Start menu search box and press Enter:

%APPDATA%\Mozilla\Firefox\Profiles

I mentioned in my first message that I cannot even start Firefox in Safe Mode when I am working with the later versions such as 32.

As for the preferences file, when I go through "Start"; "Explore," then I can find and see a Firefox folder called "Pref" which is subfolder under the "defaults" folder. Then under the "Pref" subfolder, I see a file called "channel-prefs.js" but when I double click, it does not allow me to open that file. Even if I could open that file, I would not know what to do with it.

Start your Computer in safe mode. Then start Firefox. Does it work now?

Starting The Computer In Safe Mode;

If running, turn your computer off. Remove any disks and thumb drives that are in your hard drives or ports. Now start your computer but also;

Windows; Press the <F8> key repeatedly. Mac: Hold down the Shift key. Linux; Using the command line, Linux/Unix computers can be booted into various run levels that determine which resources are loaded. For example, "runlevel 1" is typically the equivalent to Windows and Mac safe modes.

• Source; Safe Mode; Free Online Encyclopedia

When the Boot menu is displayed, release the key you were pressing. You must now choose what mode to use. The most used are;

• Safe Mode; The computer runs with only a minimum set of programs.
• Safe Mode With Networking; Same as above, but with internet access.

Hi EncinoUSA, the "AppData" folder where your Firefox settings are is a hidden folder. That's why I suggested using the %APPDATA% shortcut method to access it.

Or if you prefer to find it manually, first turn off the hiding of hidden files and folders using the steps in this article: http://windows.microsoft.com/en-us/windows/show-hidden-files

Then start from:

C:\Users\username\AppData\Roaming\Mozilla\Firefox\Profiles

Nothing has helped. So for now I am staying with Firefox version 24 that works on my PC.

Can anyone help me with my other question that I posted earlier:

<On a different Firefox topic, I imported my "Favorites" list from IE to FF, and I do see them when I go through the "Bookmarks" tab on the very top of the screen. Then under "View" tab, I have selected "Bookmarks Toolbar" which places a direct link called "From Internet Explorer" a couple of lines below the main toolbar (my idea is to save a few clicks if I want to go to my IE Favorites. However, when I click on that direct link, I only see 3 entries ("Customize links"; "Suggested sites" and "Web Slice gallery," but I do not see the many entries that should be there from my IE Favorites list. The strange thing is that until a few days ago I used to see all my IE Favorites when I clicked on this direct link! What should I do?>

If there are problems with importing the IE Favorites in Firefox then export the favorites in IE to an HTML file and import that file in the Firefox Bookmarks Manager.

If you do not have the menu bar in IE then right-click the toolbar at the top to enable the Menu Bar.

• Export the favorites in IE to an HTML file (bookmarks.html):
  File > Import and Export
• Import the HTML file in Firefox:
  Bookmarks > Show All Bookmarks > Import & Backup > Import Bookmarks from HTML

See "Import from another browser" and "Import from file":

• http://kb.mozillazine.org/Import_bookmarks

I have already successfully imported my IE Favorites to Firefox. But the problem is that I can only see them by clicking on the Bookmarks tab in the toolbars. What I want to do (and what I used to be able to do) is to also see them when I click on the "From Internet Explorer" link that I have placed a couple of lines below the main toolbar. I am trying to skip a couple of extra clicks.

Hi EncinoUSA, you can move the "From IE" folder from the Bookmarks Menu to the Bookmarks Toolbar (this is easiest when using the Library dialog (Ctrl+Shfit+b) but there's no way to create a shortcut in one place pointing to the folder in the other.