said by russshoe:I have been using Shields Up now I ran your scan ant it says all blocked
That is unusual. My experience has been that the GRC ShieldsUP! site is more prone to missing open ports than it is to classifying blocked ports as closed or open. That tendency was actually one of the reasons I setup my own external port scanner site (its scanning method is slower, but less likely to miss an open port). I just checked the GRC ShieldsUP! site again, and it is still IPv4 only, so an IPv6 backdoor should not be what you are seeing from testing at that site.
Are you still seeing the NBT and SMB ports reported as closed instead of stealth at the GRC ShieldsUP! site? If this is something that happens randomly, my suspicion would be that you have UPnP enabled on your router, and some application/device is randomly changing your router's firewall rules. I don't know about your router, but some router's don't totally disable UPnP even when told to do so and that can cause symptoms such as you are seeing (my Netgear WNR1000 is one of those routers, and that is one of the reasons why it has been demoted to being a guest router with no access to my LAN).