Server-hosted games - machine going to sleep?

[ceremony]

I've been running an Online (server) game for a few months now, and have noticed that occasionally players report that they are unable to connect, despite having the correct IP/port info.

I thought this was a firewall problem, but lately I have noticed that in another game I'm playing in, I get the same problem. However, when I telephone the person hosting it and ask him to check the server, I'm always able to connect shortly thereafter, despite the fact that he says he didn't do anything except move the mouse to check if the computer had frozen. So perhaps it is that the computer is going to sleep? Shouldn't a port request to the game wake it up?

Is there a way to turn off the "sleep" function in the system when using Windows?

Also, a note for people planning to host server games: if you minimize the server game to the taskbar, the game will take forever to process information. It took players up to five minutes just to end their turns. Dom2 doesn't like being minimized!