DNS Problems - could NIS be to blame?

A couple of days ago I was having problems accessing websites, getting Page Cannot be Displayed. At first it was sporadical, say once an hour, but then it got much worse. This was on IE11 and Chrome too.

Only restarting the PC helped. I ran Windows Network Diagnostics and it said my 'DNS Server might be unavailable'.

When I asked if it was only me having the problem, a respected MVP/Insider/Community Moderator and Wiki Author (so you know) said this: 

"I'm afraid so, yes. ( If there were any general problem with this site, then you wouldn't be the only one reporting it. Since you've now established that the problem you've been facing recently arises from your own DNS arrangements, you'll have to do a bit of troubleshooting to find out why this is happening. It might be, of course, that your ISP's DNS server is playing up - but then you'd have checked that, wouldn't you ("Contact your network administrator or Internet Service Provider ..."), visiting your ISP's forums to see whether others are having the same problem.

A straightforward way of testing this is to switch to a DNS server that you can be reasonably certain isn't playing up, like the OpenDNS servers. These are dotted around the world and there's a magic system that makes sure you connect to the closest or otherwise most effective one. If the problem with 'page cannot be displayed' persists, then the problem is not with the DNS server and may be closer to home. To change DNS servers to those operated by OpenDNS,

1.Right-click on the network icon Image in the notification area and select Open Network and Sharing Centre
2.Click on the active network connection, assuming there's only one, to open its Status dialogue.
3.Click on Properties and give permission if necessary to open the network connection's properties dialogue.
4.Click on Internet Protocol Version 4 (TCP/IPv4) and then on Properties.
5.At the bottom of the General tab, select Use the following DNS server addresses and then fill in these figures:
 208.67.222.222
 208.67.220.220
6.Click OK and then Close, Close, Close ...

Restart your browsers and try visiting some pages that have proved problematical. If you still have the same problem, please take it to, for example, the  Windows 10 networking forum where the experts in this sort of thing hang out."

But then at the end of hid reply he said this:

"[If you really wanted my candid opinion, I'd place the blame for most of your tribulations on your Norton software.]"

Can there be any truth in this?

PS I searched and there were very many results but why oh why can't they be shown in date order?

yes - that's what I thought, even with my limited teccie knowledge. Two or three on the MS forum, including an MVP, consistently look to blame Norton for any problem.

It would not be a Norton problem.  Usually the way to fix this issue is to flush the DNS cache and clear your browser's history.