Hello
If you’re using MSN on the outdated version of Windows like Win XP, we’ll get the Error 66.
However on the Win 7 to Win 10 we can resolve the issue by below troubleshooting steps.
Confirm the data and time on the computer is correct, as per your time zone
Reset Internet Explorer
https://support.microsoft.com/en-us/help/923737/how-to-reset-internet-explorer-settings
Add Additional Features
Go to control panel > Right click on MSN select Uninstall/Change
Select Install Additional features from the Installation Wizard
Sign in with the email account and follow the wizard
Restart the computer
Note: If you see all features are up to date, please click on OK.
If Issue persists please follow the below link to contact the MSN Technical support team.
https://support.microsoft.com/en-us/contactus/msn/explorer-tech-services/
Thanks
MSN Support Team