Mick, in re-reading this entire thread, no where do I see any of us recommending running Dial-a-fix, which surprises me as it often resolves weird networking issues.

Please download and unzip it, then run dialafix.exe (it doesn't need to be installed).

Check the Fix SSL/HTTPS/Cryptsvc box
Under Registration Center, check
  • Programming cores/runtime
  • Explorer IE/OE/shell/WMP
  • Object linking libraries (OLE)
Click on GO to start the repairs.

Check your computer and see if things are any better. If not, start Dial-a-fix again and click on the Tools icon (looks like a hammer).Select
  • Flush DNS
  • Reinstall BITS
  • Reinstall Windows Firewall
  • Reinstall WMI/WBEM
  • Repair Permissions
  • Reset networking interfaces
Click on GO after selecting each one as you can't do multiple selections.

Try the computer now and see how it behaves.