Old Mozilla Firefox

[irban]

I keep getting a message that Mozilla Firefox is not responding because OLD Mozilla Firefox is still running. This may account for my computer being so slow. Could someone help me to uninstall this please

[Buenchico]

See here:
https://www.thewindowsclub.com/firefox-is-already-running-but-is-not-responding

[Buenchico]

Addendum:
I'd also suggest refreshing Firefox to its 'out of the box' state:

Make sure that you know the names of any extensions you're using (such as Adblock Plus), as you're about to delete them (but you can add them back afterwards, of course). Click the three lines (top right), then 'Add-ons' and 'Extensions'. Write down any relevant names.

Then click on the three lines again, followed by 'Help' and 'Troubleshooting Information'. Click 'Refresh Firefox' (top right).

Reinstall any extensions that you want back. (Three lines, Add-ons, Extensions, Search).