If you are trying to give computer advice and would like to seem credible, for the love of $deity(s), don’t say “virii”. That is not even a word at all, let alone the plural form of the word “virus”! You’re doing it because you think it makes you sound smarter, since you obviously know that the plural of “radius” is “radii” and/or that the plural of “cactus” is “cacti”…but that does not apply to “virus”. All of those words end in “-us”, but “-ii” is not the automatic way to form a plural for a word ending in “-us”. Although the word comes from Greek, and sort of takes a side trip through Latin, historic use means we get some wiggle room with “octopus” because although “octopuses” is more correct (in English–Greek would be “octopodes”), even The Grammar Nazi isn’t going to beat you up for “octopi” (probably give you an odd look, but it’s technically acceptable). Same for hippopotamuses/hippopotami, though I think it likely that I’d have to stifle a grin over hippopotami! “Virus” comes from a Latin word that meant poison or venom. Poison/venom cannot be counted (if you measured it, you’d be counting the units of poison, not the poison itself, and if you sorted different types, you’d be counting the types), therefore the word had no plural. “Radius” did (and does still!) have a plural form in Latin, so English follows the Latin rule to make the plural, and we get “radii”. The singular “virus” is an English word with a Latin root that had no plural, so use the English rule to form the plural, which will give you….viruses, and the bonus of not coming across as an ignorant, yet pompous idiot. Yay, you!

P.S. Data is plural. “The data show…”, not “the data shows…” The singular is datum, and since we’re on the topic, the same goes for bacteria. No matter how sick one’s fish, one never encounteres “a bacteria”; it’s “a bacterium”. .