I am running Windows 8 and Norton is blocking my Allshare on my Samsung.I never had this problem when I was on iMac.
What can I do to stop Norton blocking my filesharing sites and allow access to Allshare?
well to be totally honest with you IMO Norton has seen better days (circa 2002) since then it has become increasingly less user friendly to the point where many IT enthusiasts simply avoid using it. Personally I prefer to use the default Windows Defender coupled with Malwarebytes. This is an extremely effective barrier to infection that is used by many and is totally free.
(I would un-install Norton and then use the removal tool to make sure it's all gone)
Norton removal tool: