If you have anti-virus protection then you can try disableing the Windows firewall and if that don't work you can always reenable it.
Thanks for your reply but as I mentioned in my post, I thought the network sharing problem 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 I cannot adjust the settings in Windows Firewall.
This is probably what is causing the sharing problem. So know I cannot disable or make any adjustments to Windows firewall on my DESKTOP PC