As usual reality is murky. Hardware checks including shorter memory tests were done, but this computer could not be on overnight. The prolonged test could be r

As usual reality is murky. Hardware checks including shorter memory tests were done, but this computer could not be on overnight. The prolonged test could be run when the user was out for a day. This wasn't a corporate machine but a private one. As always several OS software configuration and driver issues were incrementally discovered and rectified, and as the crashes only happened very infrequently there was always the (wrong) thought of 'this might have been the problem', only to be refuted several days to a week later. I'm not claiming I couldn't have done a better job on this one. Low frequency errors without a clear trace will always pose a challenge.