AV researchers noticed that the Conficker worm ‘woke up’ and has started replicating a piece of data among infected computers. It is still unknown what this mystery payload is, but it could be something as dangerous as a keylogger.
Bottom line is that you should check your Windows systems again for up to date virus definitions and security patches. You should also make use of a couple of free online checks: the Conficker Eye Chart (makes sense when you see it) and another test at the University of Bonn.