imagevenue have some kinda advertising pop-up that rears it's ugly head every now and then. Usually when using iv for the first time after a short period of inactivity.
My advice ... kill the pop-up as soon as it appears, then re-click the iv link. Should be fine.
I don't use Norton, but I would imagine that Norton is diagnozing the problem as a 'false positive'. In any case the pop-up is a pain in the ass.