as CloudFish and Silver said;
Norton will think it has a virus, if you try checking with SpyBot, it will not show anything about FH being a virus. Norton sometimes thinks some things have virus' when they don't. When I got FH for the first time, Norton said it had a virus. I checked on SpyBot, and it never showed anything up about a virus on FH. FH doesn't have virus' but FH+ might, because everyone I know well, said that it has a virus, I'm not sure if it REALLY has a virus, so just stay on normal FH for now