Registry value¹

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Authentication\LogonUI\UserSwitch\Enabled needs to be set to 1.

Registry permissions²

The user "SYSTEM" changes the value back from "1" to "0"
So the goal is not allow the user "SYSTEM" to change it.

• Right mouse click at registry key "UserSwitch" -> "Permissions"

• "Advanced" -> User "SYSTEM": "Disable inheritance"

• Change owner from "SYSTEM" to group "Administrators"

• Group "Administrators" -> Allow -> full control.

• "Advanced" -> User "SYSTEM" -> "Edit" -> Type "Deny" -> "Show advanced permissions" -> "Clear all" -> check only "Set value"

Control Effective Access:


Result:

Windows Win8