I am running Windows 7.  I tried Windows 10, but reverted back to 7.

In Windows Live Mail 2012, I am now unable to delete any messages in my Inbox, whether read or unread, - all I get is a message indicating an unknown error has occurred.  I'm also unable to access the properties on many of those emails.

I've tried repairing Live Mail via the Control Panel, then deleting and reinstalling it.

How can this be cured?