Issues with the Outlook plugin are often caused by updates to Outlook.
The plugins functionality will depend on your version of CRM, the version of the plugin and the version of Outlook.
We are happy to advise on known compatibility issues should this be required but we are unable to promise we can restore the functionality.
If Outlook is feeding back the error A runtime error occurred during the loading of the COM plug in then reinstall the plugin and quit/restart Outlook.
Please note that the Outlook plug in is NOT compatible with SSO
