system
15
You might open an elevated CMD window and type the command:
SFC /VERIFYONLY
This runs the Windows System File Checker to see if all files under system protection are as expected.
If this returns any errors, that could indicate that malware (or something) has modified your Windows system files. There is a similar command to correct errors. The one listed above just checks; it doesn’t attempt any restorative activity.
-Noel