I have 4 Windows 10 machines at home, and one of them is showing the infamous "going to sleep" problem. That PC goes into sleep after about 15 seconds of inactivity.

-If I reset the power setting and create a new power setting (e.g., sleep after 2 hours), the PC works normally for a day. Then, the next day it shows the "sleep problem" again.
-The system files are OK, and no hardware issues have been found.
-Another Win 10 machine has the same motherboard, CPU and graphic card as the problematic one, but doesn't show the same sleep problem.

So, something keeps changing the power setting. Is there a way to find a culprit?