There was a pre Win 10 launch update to Norton Internet Security which made it Win 10 compatible. On one pc without the NIS update Win 10 killed it - restored by a fresh download from Symantec, had to pick an older version as the existing and the website then offered the latest version for downloading.
Only problem notices so far is MSMoney squealed for IE6, a web search found a registry patch which solved the issue.
Win10 has however not resolved the lost internet connection problems I have when using trying to search using google.