Windows 10 auto-logout on <5 minutes of inactivity

Solution 1:

This is most likely happening due to a hidden power option called System unattended sleep timeout. On my machine it was set to 2 minutes, which was mighty annoying, as it would cause behavior described by OP (sleep, wake-up, login screen, Event Viewer saying: "The system is entering sleep; Sleep Reason: System Idle"). You have to enable this option in registry before being able to change it.

From http://answers.microsoft.com/en-us/windows/forum/windows_10-windows_install/windows-10-keeps-going-into-sleep-after-1-minute:

1. Click on the windows icon
2. Type regedit
3. Right-click on regedit icon, click Run as administrator
4. Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\238C9FA8-0AAD-41ED-83F4-97BE242C8F20\7bc4a2f9-d8fc-4469-b07b-33eb785aaca0
5. Double click on Attributes
6. Enter number 2.
7. Go to Advanced power settings (click on Windows button, write power options, click on Power Options, in the selected plan click on the Change plan settings, click on the Change advanced power settings).
8. Click on the Change settings that are currently unavailable
9. Click Sleep, then System unattended sleep timeout, then change these settings from 2 Minutes to 20 for example.

This solved the issue for me.

Solution 2:

There is a screen saver setting hidden in the old Control Panel from previous versions of Windows. To get to the setting, follow the steps below:

1. Open the start menu up and search for "Control Panel"
2. Go to "Appearance and Personalization"
3. Click on "Change screen saver" underneath Personalization on the right (or search in the top right as the option appears to be gone in recent version of windows 10)
4. Under Screen saver, there is an option to wait for "x" minutes to show the log off screen (See below)

If you uncheck the checkbox, you should be able to prevent your computer from logging off.