Trojan Zero.Access infection

Norton scan found two threats.

ntos (Trojan.Zeroaccess!kmem) which was removed and mrxsmb.sys_backup (Trojan.Zeroaccess!inf2) which could not be removed. It said to get the tool from the website and so I did. It did not remove anything andsaid "no threat was found" then it said to run the Norton Power Eraser and so I did. It couldn't remove it as well. On the website it said that if neither of those work, I should run the Norton Bootable Recovery tool and so I did. Again, it found but could not remove the threat. Looking through the Security History I see that I8042pr.dll (Trojan.Zeroaccess!inf) has been detected and blocked two months ago. Looking throught the forums, seems like there is no universal solution fto remove this threat, so I don't want to mess anything up here.