Windows computers no internet

[#1]

I note from your original post that you have done a scan for spyware. Did anything at all show up.  I still suspect a network settings issue here. What does a trace route show to plusnet?

[#2]

You previously said you tried using Safe mode?
Can I suggest you try again but use 'Safe mode with networking'.
And connect laptop to router using ethernet cable.  Make sure wireless is turned off.

Are you using free or paid version of Avast?
Are you sure no other 3rd party firewall app is also installed like Peerblock?

If Safe mode is successful, I would suggest using System Restore, and restore to a point in time before these problems started happening.

[#3]

Fixed- problem looks like a System Update in Avast which I fixed by system restore. Thanks for  all the help.