Microsoft has warned Windows users to be on their guard against a piece of rogue antivirus software passing itself off as Microsoft Security Essentials.Security essentials 2010 is a piece of software Microsoft said installs a fake virus scanner on your machine and]monitors and blocks processes it doesn’t like.
http://www.theregister.co.uk/2010/02/26/microsoft_security_essentials_rogue/
http://blogs.technet.com/mmpc/archive/2010/02/24/if-it-calls-itself-security-essentials-2010-then-it-s-possibly-fake-innit.aspx
http://www.microsoft.com/security/portal/blog-images/fakeinit_scan_result.png