Out of Sight, Out of Time - S1.E16

Using the Troid virus which has been sent into Jennifer's pom-poms, Malcolm is able to make the world around Sam disappear completely when each victim picks up the pom-poms, and the victims end up in syberspace, stored onto floppy disks! Sam is the only person he knows that is left, and comes to the realization that the virus is responsible for the disappearance of everyone he knows.