W7 Windows Firewall settings cannot be accessed

W7 Network
Am no longer able to share files between my laptop and desktop.
The problem is my Desktop PC which is denying access to incoming files.

I thought it might be related to the Windows firewall settings on the Desktop PC When I tried to open the Windows firewall I got an error message

0x80070724 indicating you cannot adjust the settings in Windows Firewall.

Thinking I may have a virus or a rootkit problem I ran several antivirus programs as well as Malawarebytes, and found no serious problems.

Also ran MS Windows Firewall Fixit software with no success.

How do I repair the firewall problem ???

Thanks for your help