jotaro__

Some more ideas:

• Windows update appears to have a a way to log you back into you latest session
• BIOS power on after power loss setting, you might experience brownouts
• check task scheduler (taskschd.msc) for any entries that have permissions to turn on the system
• check the system or windows event logs for any mentions of reboot during nighttime
• disconnect ethernet cable for debugging purposes
• get a surge protector power strip with a switch