Read these two articles, and please, please, keep your virus definations up to date.
http://news.yahoo.com/s/infoworld/20080313/tc_infoworld/95949;_ylt=Am_mapSP5LbfyXmlFNbb8T663MMF
http://www.abcnews.go.com/Technology/PCWorld/story?id=4441255
Good luck.