Earthdawn, the prequel RPG of Shadowrun, features the world just after the previous mana peak in the 4th world. At the mana peak, Horrors rampaged through the world, corrupting astral space, people, and anything else. In Shadowrun, this is supposedly also going to happen at some point, but the point at which it should happen should still be centuries away. The Great Ghost Dance messed with that, though. Harlequin may have fixed it again. Nobody really knows. But when the Horrors do show up, Insect Spirits and Shedim will be just a little warm-up. There was one Horror that was knows as "the Eater of Great Dragons" (though he didn't show up in the 4th World, I believe).
But yeah, that comment about corruption with the matrix going down did make me wonder if it was possible that Horrors could invade both astral and cyber space. Why not, actually?