Admin account logging out

Greetings! I have a fresh installation of 10.5.x Server on a G5 and I'm noticing something that I haven't seen on any OS X Server before - it's logging me out after a period of inactivity. I currently have one account on the machine, and this is happening when I'm logging in on the machine itself. It's in a small office environment, and there are no security concerns with access. I'd like to just have the screensaver password, but it's logging me out completely. I have Googled, Binged, Yahooed, Dogpiled, and dug through the Apple Discussions to no avail. I did see another similar thread, but no answers. On OS X 'client' I know that the "log out after X minutes of inactivity" is in System Preferences -> Security, but on my server there is no such option. ("Security" is there, but there's nothing about logout.) I've looked everywhere I can think of in Server Admin and Workgroup Manager but no dice. And like I said, I have not seen this happen on other 10.5.x Server boxes...just this new install. Help! :D