Let’s do a full clean re-install; Download Firefox For All languages And Systems {web link}

https://support.mozilla.org/en-US/kb/get-latest-version-firefox-windows-xp-vista

Save the file. Then Close Firefox.

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86)

Mac: Open the "Applications" folder. https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

Linux: Check your user manual. If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it. See Install Firefox on Linux; https://support.mozilla.org/en-US/kb/install-firefox-linux

If you downloaded and installed the binary package from the Firefox download page, simply remove the folder Firefox in your home directory. http://www.mozilla.org/firefox#desktop ++++++++++++++++++++++++++++ Do Not remove the profiles folder.

Look for, and rename any Mozilla or Firefox program folders by adding .old to them. Do not rename the Mozilla Thunderbird folder if there is one.

After rebooting the computer, run a registry scanner if you have one. Then run the installer. If all goes well, remove the OLD folders when you are done. +++++++++++++++++++++++++++ If there is a problem, start your Computer in safe mode and try again.

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode This shows how to Start all Computers in Safe Mode; Free Online Encyclopedia

Hi FredMcD,

I am thankful for a quick response but I am now running already against one of the problems described initially, and it is now even worse.

I cannot download the file (I choose English US and tried others) you are advising.

It says "unknown time remaining" and then says "Failed".

Also tried IE, same problem...

So what do I do now??

Many thanks already.

KR,

Mokum

Boot the computer in Windows Safe mode with network support to see if that has effect in case security software is causing problems.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• http://www.7tutorials.com/4-ways-boot-safe-mode-windows-10

Do a malware check with several malware scanning programs on the Windows computer.

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware

Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure 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

Using another computer, Download Firefox Full Version For All Languages And Systems onto a thumb drive. After, plug the thumb into your system. http://www.mozilla.org/en-US/firefox/all/

https://support.mozilla.org/en-US/kb/get-latest-version-firefox-windows-xp-vista

Hi FredMcD & cor-el,

Sorry for the late response but it took a while for taking all the steps and running the various anti-virus-malware tools, little time when home from the office…

Anyway, as I was mentioning that I also could not download the FF install file via IE made me realise that my problem might not be FF but perhaps something else.

And it did, one of the things all browsers have in common is that they are controlled/monitored by the virus protection SF running on my desktop.

So I googled “AVG slowing down browsers” and guess what…their site is full of complaints related to my problem, even found posts from just a week ago.

Then I figured, let’s check the control panel to see what has been updated on 1 July 2017…yep, it was AVG!

Logically I removed AVG and even all files still stored in the folder program files using an ‘unlocker’, ran CCleaner several times and then replaced it with Karspersky.

And now everything is running ‘as should’ no problems at all anymore…

I am sincerely thankful for your help and support; I have learned another lesson as a non-techie…

All the best & kindest regards,

Mokum

Lastly...

I hope when other users read this, they also consider to check their anti-virus-malware software and the impact it might have...

Mzzl,

Mokum

As a footnote, Vista users should update to the "Extended Support Release" of Firefox 52 instead of the standard release of Firefox 54.

See: Firefox has ended support for Windows XP and Vista

Full installers in numerous languages: https://www.mozilla.org/firefox/organizations/all/

Mokum said

I removed AVG . . . . . And now everything is running ‘as should’ no problems at all anymore…

That was very good work. Well done. Please flag your last post as Solved Problem so others will know.