Q: Firefox crashes the whole laptop I have a Thinkpad T410 running ubuntu 18.04 without any problems so far.
Now I reinstalled with 22.04.
When starting firefox the laptop freezed completely.
So I booted ubuntu 20.04 from installation media and tested firefox. It was working well.
Therefore I decided to install ubuntu 20.04.
I started firefox and it did not work (window not reacting), but I was able to close it.
The next time I started firefox it freezed my laptop completely again.
All testing was done with a fresh user account, with no .mozilla directory.
Now I am completely confused: Why was it working on the live media, but not after installation?
Obviously a computer without a browser is pretty useless nowadays. What can I do to get firefox running?
I did not discover problems with any other application so far, but did not test many.

A: First try Firefox in safe mode. You can try to troubleshoot there.
You can open it in terminal by writing firefox -safe-mode (you may need to specify the Firefox installation path e.g. /usr/lib/firefox) 
Also check your themes and extensions if you have any. They might result a crash too! Lmk if it worked

A: Starting in safe mode using firefox -safe-mode from the terminal solved this problem on my Lenovo T410 which exhibited the same issue of Firefox or Chrome crashing (many thanks to 'Noobish Coder' for suggesting that!!).
When in safe mode, in 'firefox settings' I then switched off 'use graphic acceleration': General panel --> Performance --> uncheck 'use recommended performance settings' --> uncheck 'use hardware acceleration'. I then quit in safe mode, opened firefox normally by clicking on the icon, and it worked without crashing.
