I changed something on my PC and not sure what! /bonk

If I am logged on and walk away and leave the PC idle for more than a few minutes it logs me off to the log on screen automatically.

If I am browsing or moving the mouse it is fine, but if I stop what I am doing and dont touch the mouse/keyboard for more than a few minutes, It logs me off automatically. Its not a screensaver as they are disabled.

What did I do? How can I stop this?

Please advise!!

Cory