Kernel Panics With Firefox 63.x

[B J]

I recently upgraded my system and that included Firefox.  It's been
troublesome ever since.  Often, it would crash for no apparent reason
and this morning, it started taking down my entire system.  The result
was that my machine would have to reboot.

Now I can't use Firefox at all without having my machine going into a
kernel panic.

My machine is more than 10 years old and I think it runs 32 bits.  The
OS is FreeBSD 11.2 and I'm using Mate as a desktop.

Any suggestions?  Thanks.

B. M. Jatzeck