I'm not a Norton user , or a fan of their software , so it would be unfair of me to blame it. As you yourself suspect it's at the root of the problem then i guess you need to decide what's best. As everything seems to work with Norton removed you can leave it uninstalled and replace it with alternatives ( we can help you choose if you wish and they can be had for free ) , or , you could try to reinstall it to see if the situation returns. For me , I'd suggest as you've got everything up and running again to go for the first option.