Illegal operation attempted on a registry key that has been marked for deletion – Error in SharePoint Site
SharePoint site gave an error message in browser “Illegal operation attempted on a registry key that has been marked for deletion” .
Resolution:
Not sure, What went wrong, But I did an Application pool recycling, which made the site up!!! When the same error occurred during a Search, I Restarted “Search Query” and “Site Settings” Services from Services on Server to fix this issue.
https://blogs.msdn.com/b/distributedservices/archive/2009/11/06/a-com-server-application-may-stop-working-on-windows-server-2008.aspx