I'm running screen inside a putty terminal. The problem I'm having is after a while of inactivity inside a screen, the screen automatically kills itself. So when I do things like run something overnight I'll come back in the morning to see that all my screens were terminated and I can't see the output (I know I can pipe it to a file but for these purposes I'd rather not). Is there any way I can stop this?
 Just to clarify, the putty terminal doesn't get disconnect. The problem happens even while I'm working in another screen. I'll be working in screen X and all of a sudden screen Y will disappear after it's been idle for a while.