The current release of Firefox for Windows XP-Vista-7-8-8.1 is 38.0.1. You can download it here: https://www.mozilla.org/firefox/all/ (scroll down to your preferred language)

However, your Firefox is identifying itself as running on Windows NT 5.0, which I think corresponds to Windows 2000, and that may be confusing things.

I assume you actually have a newer version of Windows, so I suggest turning off all "Compatibility" options here:

right-click your Firefox desktop shortcut > Properties > Compatibility tab

To take full advantage of the capabilities of your Windows, clear any settings here so Firefox does not try to behave like you have an older version.

Probably you need to exit out of Firefox and start it up again before the change takes effect.

Hi jscher, many thanks for that. I unchecked compatibility and re-downloaded and installed, that did the trick, now on 38.0.1 Do I still need to get a newer version of Windows, as I think I'm on Windows XP 2000 Home Edition, if so perhaps you could advise me how to get it ?

Windows XP is not getting any new security updates from Microsoft, so over time it becomes riskier and riskier to use it. But... if your computer was never upgraded with more memory, I don't think you would enjoy trying to run Windows 8.1 on it. (Also, it's not a free upgrade.) You may have to live with XP until you get a new computer.

Haha, how right you are, this is a 8 or 9yr.old Samsung P28 notebook. I was given it as the HDD had gone, so I had a secondhand one fitted, and apart from a board that picks up the WiFi packing up, ( bought a Belkin wireless adaptor to cure it ) that's been the only trouble. But now of course it takes years to start up, and hangs at the most inconvenient times. It's like a good old car, you get attached to it !! I wish it could be upgraded, but it doesn't meet system requirements.So will just have to plod on till it ( or I ) become extinct. However,thank you for your support. I may well have to seek your advice in the future. Christopher Burgess.