I had this error when opening windows firewall with advanced security:
There was an error opening the windows firewall with advanced security snap-in.
Error code: 0x6D9
What is the best way to solve this?
The Microsoft automatic diagnoser and fixer fixed it (seemed to be some kind of printer conflict in my case):
In case the link breaks, the following might be good search terms:
Microsoft Automatically diagnose and fix problems with Windows Firewall