http://www.symantec.com/norton/support/kb/web_view.jsp?wv_type=public_web&ssfromlink=true&sprt_cid=3428e850-c24a-4b37-967f-52baaa78a9cb&seg=hho&ct=us&lg=en&docurl=20080818112851EN&ln=en_US?Open&src=oemfaq_con_nam&seg=hho
this link above will help to update virus definitions manually. sorry it is so long, but that it is what it is.