MS has released a new tool to remove spyware and other junk, it is similar to Spybot and Ad-Adware who also removes spyware and trojans. It is a good idea to run such tools once in a while and especially if your computer behaves strange.
But it is still a Beta (final test) version, so read the release notes fist, especially if you use Windows media extender or work on a centrally administered computer at work .