Interactive logon: Machine inactivity limit
This computer-level security setting specifies how many seconds may pass without user input before Windows locks a signed-in session.
since 0.9.8.11
Purpose
Security policy: [Registry Values] MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System\InactivityTimeoutSecs = 4,900
Setup Foundry sets this value only when you select the “Lock screen after 15 minutes of inactivity” option.
This computer-level security setting specifies how many seconds may pass without user input before Windows locks a signed-in session. The value uses the REG_DWORD data type. Setup Foundry sets it to 900, causing the session to lock after 15 minutes of inactivity.
Locking preserves the session, but the user must authenticate again before accessing the desktop and its open applications.
Notes
Additional effects
When this security setting is active, Windows can also lock the device when the screen saver starts or when power settings turn off the display. The device may therefore lock before the configured 900-second inactivity period has elapsed.
Security
Automatic locking limits the time during which another person can directly use an unattended, already authenticated session. It does not encrypt data, terminate running applications, or prevent access by accounts that are authorized to unlock the device.
Possible side effects
Users must unlock their sessions after extended periods without input. This can interrupt workflows in which a device is monitored or used without regular keyboard, mouse, touch, or other user input.
Notes
Setup Foundry sets InactivityTimeoutSecs to 900 only when you select the “Lock screen after 15 minutes of inactivity” option. If that option is not selected, Setup Foundry does not set the value, and Windows does not lock the screen automatically because of this inactivity limit. Independently configured mechanisms—such as a password-protected screen saver, display power settings, or policies applied by another source—may still cause an automatic lock.
An absent value or a value of 0 disables this specific inactivity lock. Microsoft documents a valid range of 0 through 599940 seconds. The security setting has been available since Windows 8 and Windows Server 2012. Microsoft describes the lock as being invoked through the screen saver and notes that the screen saver should be active on the destination device.
Microsoft documentation
Microsoft Learn: Interactive logon: Machine inactivity limit
Microsoft Learn: Machine inactivity limit policy and registry value