Thanks for all your help.
I have further found that the Windows Defender Advanced Threat Protection is the one service that will not start no matter what I try.
Access is denied.
Error code 5.
It is stuck on Manual.
Without that of course Windows Security will not function.
Thanks for the detailed reply.
I had already done all the above and other suggestions from the web after installing the Win 11 upgrade and discovering the Windows Security Issue, before posting on the forum and before installing Kaspersky.
However I uninstalled it using the tool recommended and...
Thanks but this does not work either.
It relies on Windows Security running correctly I think.
It shows the functions but cannot do a quick or full scan.
I therefore don't know if I am getting protection through Windows Security...
I have also done 2 repair installs as well.
They did not fix this issue.
I don't want to do a clean install as everything else works fine.
I will use a 3rd part AV app instead.
Too bad as I was using Defender on Win 10 with no issues.
Thanks for your help...
So I just installed latest Win 11 ISO as an upgrade over Win 10 on an unsupported PC.
All went well and the PC runs well.
Only issue so far is I cannot get Windows Security Centre to open up at all.
Clicking on the icon starts the display but it disappears after a seconds or so.
Can not start...