Just been zapped by a money scam on my Mac. Fortunately I never coughed up any lolly having a few Scots in my past!! Whilst browsing, (a clean site I may add), a warning came up stating I had a virus by a site that went by something like Mac Defender, at this stage I wasn't paying too much attention. It looks very Kosher, it recommended I down load an App called ' Mac Defender'. I did, it ran a scan of my system and advised me I had several virus'. (I didn't). To remove the virus' I had to register the App and pay!!! That was the bit I stopped at. I disconnected my Time Machine hard drive and external HDD. I found the App in my applications folder and attempted to remove it to trash. Nope - wouldn't go. Telling me the programme was running and I couldn't trash it. You cannot close the programme as you would a normal programme. It has a small red icon in the top bar of the computer. To close the programme you have to open 'Activity Monitor', stop 'Mac Defender' then delete 'Mac Defender'. Also check it hasn't attached itself to your 'Account' in System Preferences'. THEN!! Run a search in Spotlight. Then once all that is done securely delete trash. Download a programme called ClamXav, it's free, (ClamXav ) a kosher mac AV programme and run it through your computer. For confirmation, Google 'Mac Defender' for further info. Hope this helps someone from parting with their hard earned.