apparently it's the opposite of the blaster worm... it goes to windows update and downloads and installs the patch for the problem that enables it to get onto your PC in the first place.. and removes the blaster worm... and then does some pinging crap.. it's the pinging that's the problem though.. http://securityresponse.symantec.com/avcenter/venc/data/w32.welchia.worm.html