Java has constant updates...sometimes they happen a few times a week. If you are unsure if the update was really Java, try to remember what the icon looked like down on the right. The Java update icon is an orange square with a coffee cup in the middle, and during the update process, it shows you ads for things like OpenOffice and tells you what other devices Java is used in. If thats what happened, then it was most likely a real update and there is nothing to be worried about. If you still want to be sure theres no infection, try using another antivirus just to verify Norton's findings. You can use any of the popular free ones, such as MalwareBytes, AVG, or Microsoft Security Essentials. If you go this route, just be sure to remove the antivirus program afterwards...when you have more than 1 on the computer, they don't play well together and other issues could occur.