Trojan.Gen.2 / Trojan.Zeroaccess.B

Hello I've read a number of threads on here regarding this and hope that someone will be able to help.  I have not done anything yet.  I'm running Norton internet security and keep getting messages that these threats have been blocked (annoying).  I'm running Windows 7 Home Premium 64 bit OS.  I have a flash drive.  I think this is all the info. people have been providing....

Thanks,

Dave