VIRUS?!!

Herro everyone, recently I've been playin' LoL, and one day, after the champion select, the screen just blacked out with only my cursor (btw im a Mac). I was like "wtf" and went to school to ask my friends, and few friends had the same symptoms and said it was a virus. Does anyone have a cure? Cuz I really do not wan't to wipe out my CPU :D. ALSO I GOT LEAVERBUSTER... WHYYY!!!! Anyways, I'm just making sure, I think I tried all the ways possible. Restarted my CPU, re-downloaded LoL, pretty sure it is not because of a fire wall, but anyways, HELP MEE PLZZ GIMMEEE MERCYYY.... :D

Thanks!