Nevermind; I've solved the problem on my own.... I've reverted to Windows 8.1!

It doesn't work even after creating the reg keys...

Sorry, it doesn't. That is also one of the first things I do on a new OS, exactly because I hate useless notifications; at least, they're useless to me.

Sorry, I don't have that key in my regedit
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I've already disabled the tray icon, it's amongst the first things I do on a new OS and, unfortunately, the registry hack doesn't work either; the message still appears.
I'm not sure I understand...

I've never had any such problems before: I've always turned off this service: this notification has only appeared with Windows 10
The command prompt (admin) doesn't actually give you system...

Have you tried using the hidden administrator account? Maybe that could help you.

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Every time I switch on my PC, after about 5 minutes, I get this annoying notification (see picture) from my OS asking me to turn on the security center service; please, note that, on my PC, I...