I had a malware or something in my mail downloads folder sent to me from my daughter's cell phone that had internet on it. Slowly my Apple mail started acting up, then it really kind of stop loading movies. Then I upgraded the QuickTime 7.5. It killed everything. I lost all my mail and hundreds of application serial numbers, because before I realized it, I had cloned the trouble to my slave back up drive.

So I did an archive install but it still took me months to sorta get back to normal. I lost a lot.
I use to have VirusScan, but it bogged down my computer. Then went with the free ClamXav which is excellent but is a manual app and it won't catch viruses or any other stuff that damages your Mac.
It works great if you run it on a folder. It's better at finding things then VirusScan.

So now I went to the newest Norton for Mac. I left them long ago, but they work great now. I just wish they would make a new Norton Utilities just like the old one.

So if I didn't have that, I sure would try this. Since there are so many PC users switching to Macs and the world hates us. I think a Virus program is due for the Mac community.

You don't want to find out you need one after the fact.