Check if your usage is configured normally (nothing should be at 0% except Singularity).
Every time you buy PCs, buy max DSGs once and activate the black hole once. Buy all PC upgrades, money tree upgrades, CPU factories, CPU upgrades and buy max the triple GHz upgrade. Then activate black hole while buying max DSGs a few times, then buy max triple GHz upgrade and buy max DSGs. Now you buy more PCs and repeat this 2 or 3 times. If there's too many viruses, simply feed the black hole, buy PCs and feed it again until they're gone.
This is a long comment but it's really just buying everything and removing viruses with the black hole.