My uncle has had his Mac for a while, and recently he tried to install something dodgy to watch a live football match, from his Mac. However, he nearly always gets ad pop-ups now, and he's had enough. I installed Ad-Block for him, but that probably won't be enough. What's a good virus scanner for Mac, that's free, and works quickly? It needs to work in depth, but not take too long. I was thinking avast! might work, but it takes a little too long. Any other suggestions or would avast! be the best?