Seriously, if you have a Mac, do this now.
Apparently my MacBook Pro at work was infected with malware from an email that I never opened or even saw. It went straight to the junk folder, but it was too late. My laptop was running slow and hard drive space started disappearing.
I discovered the culprit by downloading a free anti virus app called ClamXav from the App Store. It caught the offending file and quarantined it. I deleted it, but it must have a rewrite code built in because it came back the next day. And that’s when I noticed the HD space disappearing. Who knows what they were using my computer for… and I really don’t want to know.
Bottom line: if you own a Mac, download ClamXav (recommended by my IT guys) and run it. It caught things that the big boys didn’t. If you like it, you can make a donation to the developer, like I did.
EDIT: As a result, I’m having to slash and burn my hard drive and pray to Steve Jobs that my Time Machine isn’t infected.