Please help. I've spent several hours online with Norton techs to no avail. Am very, very frustrated! I had a Norton Security suite installed, courtesy of Comcast. When I upgraded to Sierra, that stopped working, and was moved over to "Incompatible Apps." When I tried to re-install, installation failed. I then contacted Norton support, who spent over 2 hours connected to my machine, but were still unable to re-install the application. I saw the post that a Sierra update is available via LiveUpdate, but I can't even install LiveUpdate to get there! Need a solution. Thanks.