I've been having a few issues with ipv6 since I moved my desktop to Vista. Before on Windows XP, it was working perfectly. I have a cisco 837 router configured with a sixxs tunnel. I have my own dns server with both an ipv6 and ipv4 address and runs debian. Things that deffinately work are: - ping local network and remote ipv6 addresses - ping local and remote ipv6 dns names (e.g. ping -6 noc.sixxs.net) This tells me that the ipv6 fundamentals are working. The strangeness starts when I can't use ipv6 in any applications, about half the time. When I say about half the time, I mean that 50% of the time that I boot into Vista, it works perfectly. The other 50% of the time, applications cannot access ipv6 addresses, and don't resolve dns names to their ipv6 version. This would be better if it was consistent, but the fact that it keeps being fixed and then breaking again through a reboot is rather odd. The behaviour is the same whether I have my gateway and dns either set manually or auto-configured. Anyone got any ideas?