Google has decided to stop developing the Google toolbar, so it no longer can be installed. http://support.google.com/toolbar/bin/answer.py?hl=en&topic=15356&answer=1342452

You can try some other addons that do similar functionality to the Google Toolbar, Google Toolbar is no longer compatible with Firefox - Here are some alternatives.

Thanks but I`m becoming increasingly fed up with Firefox. It crashes too often and is slow cf Chrome.....I guess it`s just habit I still use it......I`ve had problems with some add ons......crashes......so I`ll stay where I am

If you are having issues with Firefox I'm happy to try to help you. You can try using the Firefox Reset First, it will most likely help you quite a bit with your speed and crashes. Refresh Firefox - reset add-ons and settings