DNS server not responding. Internet keeps stopping randomly.

  paulbuttrill 23:49 01 Feb 2015

For about a week now my Internet keeps stopping randomly sometimes only after 10 minutes after switching on my PC. These are the

messages I've received when I troubleshoot:

The DNS server isn’t responding

Your computer is trying to use a DNS server that is incorrect or doesn’t exist.

*Investigate router or broadband modem issues Reset the "Local Area Connection" adapter*

Windows can't communicate with the device or resource (primary DNS server) The device or resource is not responding to requests.

Local Area Connection" doesn't have a valid IP configuration" Local Area Connection

I've tried switching my PC and router off and on, changing IPv4 DNS server addresses to, &,, 'Obtain DNS server automatically, ipconfig release/ renew, uninstalling then reinstalling the network driver, switching off

my firewall (Private firewall 7.0) and Anti virus (Avast) and finally reinstalling Windows 7 (as an upgrade so as to keep my files).

It seemed to work for a few hours but then started failing again.

I've noticed that a lot of the time the 'NT Kernal & System' process in the Task Manager goes on overdrive when the Internet cuts

out. It must be related because normally it's on (or close to) 0%. I then have to restart the PC. Sometimes every 10 - 15 minutes

(unless I'm not using the Internet).

It all started going wrong when I got rid of Zone Alarm and installed Comodo. I got rid of Comodo and put in Private firewall. I've

also done Avast anti-virus, anti-malwarebytes, Lavasoft adware, Advanced Systemcare 8, Spybot search and destroy, VIT Registry fix

scans. I really don't want to format the HDD and start again. Please help.

(I had to write this in notepad first then copy it to the forum just in case it failed while I was writing)

  paulbuttrill 18:34 02 Feb 2015

Thanks but my router and Windows 7 were working fine up until last week. I thought it was something to do with the firewall but when I disabled it the problem still kept on continuing. I'm completely baffled by it all and I'm puzzled why the 'NT Kernal & System' process in the Task Manager shoots up the processor when the connection stops. I read on another forum that it was stuck in a loop. It must be related but I just don't know what's causing it.

  paulbuttrill 15:15 22 Feb 2015

I found out the culprit that's causing all this: Avast free antivirus. When I disable it everything is fine but when enabled it all starts again. I've no idea why.

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