So, basically, their answer is quite legit. 

They are correct in that reimaging should run undisturbed. However, i doubt this process takes all night. Further, not all PCs can be wiped clean every night. The servers resposible for storing the users' accounts will have to keep their data, for instance.Originally Posted by the admin people
Hello
Thank-you for your suggestion.
Overnight our cluster PCs are updated and reimaged and it is best not to run a screensaver such as SETI@home in case this vital maintenance work is affected.
Best Wishes
It made no difference if I even started and games or programs at all! No extra tasks appeared in the task manager, there was not sign of any extra processes running, it scanned clear for adware and viruses, but everything just slowed down after about 10 mins. I could even see it when the weekly full system virus scan was being done. I thought I was going to have to do a full windows re-install, but a Civ4 reinstall did it.El Mac said:Are you pausing F@H to when you play the games? I find that helps.