I believe there is a new hack out that allows a user to uber lag the server forcing it to require a manual reboot. If you start to see it get really laggy you may be able to get a reboot off in time if you bind a key to the rcon command.

Otherwise there is nothing that can be done until it is patched. I will try to install some upgraded security mods and 24 hour automated demo recording this weekend to help catch the people doing it. I will also get into contact with developers to ensure that a patch and cause can be found. Hopefully a fix could be available as soon as Monday. For now I am off to bed...