I've removed "kexec" and explicitly set "NvAGP" to "0", but my system is still very unstable.
I'm now using the latest stable kernel from www.kernel.org
"18.104.22.168", but unfortunately, this doesn't make much difference.
Are there any conflicts with the preemption options in the kernel?
Most of the extraneous junk has been removed from the kernel config. I will streamline it further....