The author of mass-mailing worm Bagle <A HREF="http://zdnet.com.com/2100-1105_2-5258179.html?tag=zdnn.alert">began distributing its source code</A> and two new variants on Sunday, which could trigger another summer of misery for Windows users. The Bagle worm first appeared in January as an e-mail attachment. Within months, there were more than 25 variants.