I too just discovered my Teredo Tunneling Adapter is now defunct. Shows a code 10. I run Windows 7 Ultimate. I have tried the reinstall and/or upgrade of new driver and it will not install successfully. The "Fix It" routine only says it found there is a problem with the adapter, but there is no fix. Troubleshooters unable to fix. Device manager shows the "Warning" triangle. Last I checked, this was working and I have been running Norton 360 for over a year. I do know there were just recently 4 or 5 windows updates and I wonder how far back one has to roll the computer to catch whatever update may be the culprit - if indeed that is the problem. Device manager does not show this as a 'psuedo interface', but the teredo tunneling adapter. Suggestions to check with the manufacturer have me stumped since mine says Microsoft, yet i don't have $59 for customer service support for something I should be able to fix. Since it is network related however, I am hesitant to troubleshoot beyond what instructions I have seen so far - I don't want to lose IPV4 AND IPV6 both! Any advice is appreciated. I am stumped and very, very frustrated.
FWIW - ran every troubleshooter there is to determine if there were any related errors. All report everything is well - except the teredo.