I have just had a bit of a shock. Norton told me that it had fixed some adware problem on my Windows 7 PC. I looked up how to get rid of it totally and ran adwcleaner and malwarebytes. I let it remove everything that looked like the problem, saving files I know I use. Since then, when I try to access the internet I get the message DNS Server not responding. There was certainly no item in the files removed by either program that mentioned DNS in any way.
My PC normally accesses the internet via a router on a home network.
The PC is a LAN wired connection.
It can see the router in a browser if given an IP address but not the name.
In Windows Explorer it can see all the other devices on the network and access files on them.
The router sees the PC as connected with the correct name.
The DNS Client is running on the PC.
It fails even in safe mode.
I have cleared the DNS cache and re-booted both the PC and the router.
The PC is set to obtain a DNS address automatically, as are the other devices on the network that are working.
I can't think of anything else that would be relevant at the moment.
I live in hope that someone can help me identify what may have been corrupted while trying to clean the PC.