Here's what to do when your PC not running the screensaver or refusing to go into sleep/hibernate mode.

[bjornk]

(For Windows only)

 

1. Type CMD and run it as administrator.

2. Type powercfg /requests

3. Find the culprit.

 

My screensaver had never run since yesterday even though I hadn't touched the PC longer than the required time for it to trigger, so I figured that something had kept it from running and it was indeed Chrome. It kept telling the system that it was "playing a video" even though it didn't. To fix the problem, all I had to do was to restart Chrome. Powercfg /requests returned an empty list after that.