I currently work at a school and we have been infected with this virus and it has been spreading throughout the school district.
if you use USB stick / storage and similar here is a special tool that target those bugs (network worms and similar) that use removable drives to spread

totally free and fully automatic. just install (on all school computers) and forget: MCShield http://www.mcshield.net

Reviews http://www.mcshield.net/reviews.html click to read