I received an unexpected shutdown and subsequent 'This problem was caused by
Realtek RTL8168/8111 family PCI-E Gigabit Ethernet NIC (rtlh86 .sys).
The advice was to go to Windows Update to install latest drivers, which I
did, and it took a while.
I continue to get exactly the same shutdown error up to five times a day.
Any other steps I can take to resolve this matter that you can suggest would
be much appreciated.