What were you doing at the time? surfing, watching a clip, reading something . . . .

Start Firefox using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

Tried start up with shift, after previously allowing a minute for all running versions to close. 5 running versions of Firefox at startup. At the first time it started, A week or so ago, I was browsing online news paper Mirror.co.uk. Then it started doing it on Gazzettelive.com, an affiliate of Mirror, Now started locking in a free postcode lottery site

Now started locking in a free postcode lottery site

You may have ad/mal-ware. Further information can be found in this article; https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no

Run most or all of the listed free to use malware scanners. Each works differently. If one program misses something, another may pick it up.

Many site issues can be caused by corrupt cookies or cache.

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

• Delete cookies to remove the information websites have stored on your computer {web link}

• How to clear the Firefox cache {web link}

If there is still a problem,

Start Firefox using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

While you are in Troubleshoot(Safe) mode;

Try disabling graphics hardware acceleration in Firefox. Since this feature was added to Firefox it has gradually improved but there are still a few glitches.

How to disable Hardware Acceleration {web link}

I have Bitdefender and Trojan Remover scanning, Both uptodate.

You should run this so that you can see what's running.

https://docs.microsoft.com/en-us/sysinternals/downloads/process-explorer

It is quite normal to see more Firefox processes running.

• process for the main Firefox thread (user interface)
• one or more content processes, see:
  Settings (Options/Preferences) -> General -> Performance
  remove checkmark: [ ] "Use recommended performance settings"
• process for the compositor thread
• process for extensions
• process for WebRender when this feature is enabled

You can find the current multi-process state on the Troubleshooting Information page (about:support).

• "Help -> Troubleshooting Information"
  "Application Basics": Multiprocess Windows
  "Remote Processes" further down

See also the about:memory and about:processes pages for information about the process IDs.

Try to start Firefox in Troubleshoot Mode to see if that works.

• Windows: hold down the Shift key while starting Firefox
• Mac: hold down the Options key while starting Firefox

• https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode

I half expected the extra sessions to be add-ons but they are all supposed to be turned off in troubleshoot mode. In troubleshooting info, under add-ons the 3 I installed all show disabled, but 6 show enabled, Amazon, Bing, DuckDuckGo, ebay, google and Wikipedia. try managing add-ons, only the 3 I added show stating turned off. Jonzn4SUSE suggested ProcessExplorer, that shows main instance of Firefox with the others running below it. Same for Thunderbird shows extras running under main. I went to try a system restore and had restore points dated 11 Nov about the time this all started, I noticed one restore point named 'maintenanceservice' which is in the Mozilla Folder Turning off the performance tag did not make any difference even setting the figure to '1' Never used to show any extra sessions running only ever 1