I put my computer (Windows 8.1 Pro) to sleep every evening.
For a couple days now, I find it awake in the morning. A quick check in Event Viewer shows that it actually woke up and (apparently) put itself back to sleep again many times during the night, about every half hour.
This is new and was not happening three days ago. I have already taken great care to make sure my computer doesn't wake up for no good reason:
- Windows Update is setup to download updates but to let me choose whether or when to install them:
- Wake timers are disabled for the power plan I'm using:
I prevented all devices from waking the computer up:
C:\>powercfg -devicequery wake_armed NONE
As far as I can tell, no active Scheduled Task is allowed to wake the computer up to run.
A quick check with Windows Defender (with up-to-date definitions) does not detect any malware (not that Windows Defender is really good at finding them...)
A few more (possibly unrelated) details:
My computer has been up for 10 days now. This isn't unusual, I often reach uptimes of 30 days or more.
I often have (paused) YouTube videos open in browser tabs when I put the computer to sleep. Again this hasn't caused problems so far.
Any idea what could be causing this, and how to make sure my computer does not wake up?