AdChoices seems to come under the definition of PUP, Possibly Unwanted Programs. There have been many discussions of whether or not Norton should be blocking, or at least warning users of these nuisance programs. Norton products focus on malware that can damage your system or software, and as PUPs do not cause damage to your hardware or software, Norton does not use up your system's resources looking for these, They can be annoying, and a pain to remove. Some users actually want the 'added features', which is another reason Norton does not block them.
As no single security program is able to protect you 100% of the time from 100% of the thousands of malware programs released every day, I would suggest a second opinion scan using the FREE version of Malwarebytes. You can find it here http://www.malwarebytes.org/products/malwarebytes_free/
If that does not solve your problem, I would suggest you look at the list of malware removal sites Dickevans has posted here. As noted by Hugh, the list is not for other AV programs.