Status Update:
- On May 8 morning, I did the following per TianjiWu's suggestion:
In Device Manager, under "Universal Serial Bus Controllers", for "UAB Root Hub (xHCI)" unchecked the "Allow the computer to turn off this device to save power" under "Power management" tab.
For the next 30 hours (1-1/2 days), there was
no sleep-crash (sleep mode enabled, hibernate disabled) during long sleeps and overnight sleep.
- On May 9 evening, Windows Update installed many "Intel Driver Updates":
For the next 24 hours (1 day), there was
no sleep-crash (sleep mode enabled, hibernate disabled) during long sleeps and overnight sleep.
- On May 10 evening, Windows Update installed "Cumulative Update...":
For the next 24 hours (1 day, there was
no sleep-crash (sleep mode enabled, hibernate disabled) during long sleeps and overnight sleep.
- On May 11 evening, Windows Update installed "Update for Windows 10...":
For the next 120 hours (5 days), there was
no sleep-crash (sleep mode enabled, hibernate disabled) during long sleeps and overnight sleeps.
- On May 16 evening, Windows Update installed "NVIDIA driver update...":
Few the next 48 hours (2 days), there was
two sleep-crashes (sleep mode enabled, hibernate disabled) during overnight sleeps.
It looks like item 1 above, made difference in stopping the sleep-crashes. For 8 days, I did not experience any sleep-crash. I tested various scenarios - plugged in and sleep for long periods and overnights; on battery and sleep for long periods and overnights
(the battery drainage while sleep was very minimal).
However item 5 above messed things up. I have had two sleep-crashes in two overnights.