i would never use norton because of bad experiences personally.i have over the years been served faithfully by the following programs; grisofts a.v.g free antivirus. p.c tools registry mechanic and also spybot search and destroy.these nailed everything until last week,i was updating p.c for xbox360 link software(microsoft site).after not being able to install the software i started having spurious problems(opening a folder and browser would try to open a page,and also pages not loading,lock ups it eventually stopped me from using my email account.after running the 3 progs above and not sorting the issues i began re installing software with no luck.i eventually found a link to a program i had not heard of but was at my wits end so decided to try it(being free).everything is now fantastic.the program...... malwarebytes anti malware.any one at their wits end its worth trying http://www.malwarebytes.org/mbam.php . i like the slogan "its like bringing an m4 to a knife fight"