How and where? You have to do more to give steps when the problem happened for anyone to replicate the problem.

Please see this support article about getting help for Firefox crashes. https://support.mozilla.org/en-US/kb/firefox-crashes-troubleshoot-prevent-and-get-help#w_get-help-fixing-this-crash

I do realise that I have not given you much to go on. The only thing I can add is the fact that crashing is probably not the right term because FF is still open and visible.

If I switch to a different tab then all appears ok till I switch back to the original tab that is still frozen. Having said all that sometimes it does in fact freeze the whole program. CTRL+ALT+DEL will not work either.

Thanks for your time, Regards Lee