Harrumph! earlier today my computer suddenly shut down then restarted. Totally out of the blue. The restart resulted in the infamous BSOD 🙁
Turned out the network adapter had finally given up. Why this should result in such behaviour is beyond me, but it did. Replacing the card with another one (same make/model so no driver worries) has meant the computer is now happy again.
In the run up to this the network card has been having some strange disconnects, so perhaps it was trying to tell me something for a while?