A better explanation for the "Long Night" would possibly be the sudden
advance of technology discovered from ancient sites and their use by the
emporor in brutaly conquering the imperium once again followed by the sudden
return of Grandfather with a good deal of wrath. After all, from all I have
read not much would escape in an attack made by Grandfather. Perhaps the only
planets to survive semi-intact would be those with low tech levels. This
sounds somewhat more plausible. (Compared to the virus idea.) Matt Teets.