The saga still continues. I first Googled the problem, and then learned that it may be a Norton Anti-Virus conflict with the latest Mozilla update 22.0.
I then followed the advice uninstalled Mozilla Version 22.0 and re-installed the previous 21.0, but then the crashing got worse than it was before. Darn!
So I went a step further and much more drastic today. My Kaspersky that I'm using for my laptop is due for renewal in a couple of weeks. It covers 3 licenses. So I brought the renewal date forward. Got completely rid of my Norton Anti-Virus software, and then installed Kasperksy from scratch. Was quite surprised how fast it took to load compared with before. I had it up and running in no time. And was totally confident I'd arrived at the answer, until Mozilla crashed again. This time round there was an improvement however, so I think Norton was still the problem. It's only crashed once tonight, and I've got at least 50 tabs open. Sort of really giving Mozilla a great work-out. I'm hoping the crash is a one-off.
Not sure what my next solution will be. At the back of my head I'm wondering whether it's finally time for me to try out Google Chrome. Give in to Big Brother.
I just hate letting go of Mozilla however. Will give it at least a few more rounds of trying different solutions, and waiting for Mozilla's 23.0 update.