What would cause the twgs.exe program to start using 100% of the server resources while the games are running. This happened at a time when extern was not running and of course, no games were being banged. I had to reboot the server to put it back to normal settings. At the time this was happening, I had no tasks running except the server software and the task manager, which made me aware of the problem.

Any thoughts?

Probably the alien server locked up, it happens sometimes. Are the aliens set to sleep when no players are in games or are they running 24/7? You can disable the alien server while the TWGS is still online and reactivate it as well, sometimes that clears up the problem without having to restart the TWGS, I hope this helps on the problem, if not, let me know.
And luck with the TWGS working right, I have had that issue and found that the Alien server was causing it.

Never thought about the aliens but it sounds like a solution to me. I'm running the stock aliens in 2 different Subzero Games 24/7, so a hangup is possible and of course, turning them off and then on again would reset them.
Thank you very much for your help, Vulcan.