DefenceLab uses a slightly different approach than most rogue security software. DefenceLab will try to trick the people into paying for the program with the use of FakeAlert pop-ups that direct people to a Microsoft Support page (http://support.microsoft.com/kb/896861).
The page is modified and links are replaced, instead of remove DefenceLab, the links actually trick people into downloading "DefenceLab".
If DefenceLab is installed on your PC, you should remove it immediately, and obviously you need to be careful where you get your uninstall directions from, be wary of anything that looks like it's from Microsoft.
You can use VIPRE to remove DefenceLab. Click here to use VIPRE's free 15-day trial to remove DefenceLab from your PC now.