It's possible auto wakeup was enabled in the BIOS, with the wake time set to the default of 00:00.
Alternatively, if it was a different time, perhaps *that* was the default, or maybe the value accidentally got changed.
Alternatively-alternatively, maybe the BIOS had a bug in it that somehow enabled auto wake without presenting an option. To tackle this, I would've reset the BIOS settings. (I once had an ADSL2+ modem that randomly started flaking out and not connecting correctly. Changed every accessible setting I could, no dice. Factory reset = instantly back to normal.)
It's possible auto wakeup was enabled in the BIOS, with the wake time set to the default of 00:00.
Alternatively, if it was a different time, perhaps *that* was the default, or maybe the value accidentally got changed.
Alternatively-alternatively, maybe the BIOS had a bug in it that somehow enabled auto wake without presenting an option. To tackle this, I would've reset the BIOS settings. (I once had an ADSL2+ modem that randomly started flaking out and not connecting correctly. Changed every accessible setting I could, no dice. Factory reset = instantly back to normal.)