Best I can guess, and I thought that guess
was fairly clear, somehow the kitty cat
stepped on some keys that got Firefox confused
about some Web page and to shutdown. Then
when Firefox started again, it kept trying to
redisplay that Web page where is was confused
and just got confused again.
To know just why
Firefox got confused likely would have to know
some details on what Firefox keeps on each
Web page it remembers in its history, and I don't
have any such details.
But by deleting the history for the day, Firefox
was no longer able to try to return to one of
the pages where it was confused and got
well again right away.
From my Google search, I saw a lot of discussion
of Firefox doing such shutdowns, and all the
suggestions for solutions were a lot of work
and looked unnecessary or even unpromising because
I'd made no changes in my software collection or
configuration. Or, Firefox was fine until my kitty
cat walked across the keys.
In the interest of a short post, I omitted this
explanation.
This discovery seemed nice because
from my Google search the problem is fairly
common and my solution was just dirt simple,
much simpler than anything else I found.
Since apparently just hitting some random
keys can get Firefox sick about some one
Web page, my solution should apply fairly
frequently, maybe to a significant fraction
of all instances of the problem, especially
to uses with kitty cats, babies, etc.
Hope that makes things a little more clear.