MENACED BY WIN32.SILLYFDC

I am taking care of 20 computers in an internet cafe when this win32.sillyfdc popped in one of the workstation. I did not panic because AVG Antivirus successfully deleted the file but the other day all computers were infected and though AVG Antivirus deleted the virus, it comes back and menaced my customers. I have tried installing Trend Micro PC-cillin, Norton Corporate, AVG OEM but still, the virus exist and menacing my network…Guys Help.