One possible reason is that one of your add-ons is not compatible with this updated version of Firefox. Another possible reason is that one or more of Firefox's program files got corrupted during the update.

Add-ons

Extensions

To see whether one of your extensions could be the culprit, could you test in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Reset).

Any difference?

Plugins

Safe Mode doesn't disable plugins. If you have security-related or other "global" plugins that work in the background, they may cause problems if set to "Ask to Activate". You can adjust the permissions on the Add-ons page. Either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins.

I suggest setting:

• media viewers such as Adobe Acrobat, Silverlight, Shockwave Flash: "Ask to Activate"

• global plugins such as password managers or security scanners: "Always Activate"

• mystery plugins: "Never Activate"

This change might not affect the current window, but should affect new windows (Ctrl+n) and all windows after exiting and starting Firefox up again.

Corrupted Program Files

Clean Reinstall

We use this name, but it's not about removing your data/settings, it's about making sure the program files are clean. As described below, this process does not disturb your existing settings. Do NOT uninstall Firefox, that's not needed.

(1) Download a fresh installer for Firefox 36.0.4 from https://www.mozilla.org/firefox/all/ to a convenient location. (Scroll down to your preferred language.)

(2) Exit out of Firefox.

(3) Rename the program folder

(32-bit Windows folder names)

C:\Program Files\Mozilla Firefox

to

C:\Program Files\OldFirefox

(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.

Any improvement?

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

• \OldFirefox\Plugins
• \OldFirefox\browser\plugins

I have tried all of these things.

Safe Mode makes no difference.

Clean install - I actually deleted the Firefox folder and reinstalled.

Nothing seems to fix it.

Do a malware check with several malware scanning programs on the Windows computer. Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure that you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  http://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked
• https://support.mozilla.org/kb/troubleshoot-firefox-issues-caused-malware

Create a new profile as a test to check if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

I have now downloaded every malware listed. Only one would work on Win XP and it found a bunch of stuff which is gone now. Nothing major.

I have created a new profile and now I can't access ANYTHING, except the Mozilla help forum.

When I type something into the address bar or the search bar, hit Enter, NOTHING happens.

What am I doing wrong? Or is ver 36.04 a complete mess?

Thank you for any real help that is available.

btw, it all works just fine in Chrome. I think I will have to abandon Firefox.

When you enter text into the address bar or search bar, an arrow appears at the right end of the box to submit it. Does clicking that work, or are both boxes nonfunctional that way as well?

Sorry. I put my reply in the other question list.

No, the arrow does nothing. Hitting Enter does nothing

In either box

Thank you jscher2000 and Cor-el for spending so much time looking into this situation. I am baffled. I guess I will use Chrome in the future.

One thing that puzzles me is your Firefox user agent string identifies your version of Windows not as Windows 5.1, which is the version for Windows XP, but Windows 4.10 which to my knowledge never existed. So something is definitely messing with Firefox but I'm sorry we haven't figured out what it is.

Create a new profile as a test to check if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

I have created a new profile. But, Firefox doesn't work AT ALL when I use that profile. I can't get into any website except the Mozilla ones that I managed to access through the tutorial.

The Search screen that comes up lets me type, but, when I hit Enter, the characters just vanish and nothing happens.

It's much more messed up than that.

I have reinstalled with a clean install. No help.

I think the only thing is to wait for the next version to be released. All of this started with this version. 36.04 on Windows XP

As to Win 5.1 vs 4.1.... I haven't a clue.

Maybe I need to reinstall Windows. I wonder whether that's even possible with XP.

Arghghgh. Do I have to move up to Win 8?? Please, no....

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) as a test.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/

Hello cor-el

That made a difference. I was not connected to the internet, but, when I typed something into the address bar, it tried to access the page. Failed, of course, but that's better than how it is now.

So, what do I do now to find out what is causing it not to work if NOT in Safe Mode???

Try to disable your security software temporarily.

If it works in Windows Safe mode then you likely have a problem with other software, possibly security software or a system driver, on your computer. You can check possible advanced settings in your security software for Firefox. Also make sure that you have the latest updates of your security software and hardware drivers.

You can use the MSConfig program or the Autoruns utility to see which software and services are getting started, but be cautious with disabling services.

• http://technet.microsoft.com/en-us/sysinternals/bb963902.aspx

I will look into this in the morning. It is night here in Nova Scotia now.

Thank you for the suggestion.

It is possible that your security software (firewall, anti-virus) 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 install 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

• https://support.mozilla.org/kb/fix-problems-connecting-websites-after-updating

This problem was solved by removing the compatibility property on Firefox. Many thanks to jscher2000!!!