STOPzilla

Does anyone know how to get rid of this STOPzilla program.  My computer is infected with a trojan virus which Norton did not pick up and now I am having trouble booting up and connecting to my school network.  This STOPzilla program came up and did a scan of my computer and found viruses and spyware.  When I cliked the fix, it required me to purchase the product before it would get rid of the threats.  I did not, and Norton did not find it.  How do I get rid of these threats?