Why do I get error "The program can't start because essupp.dll is missing from your computer" when adding a Salesforce ODBC driver data source on Windows Azure?

The Salesforce ODBC driver Setup program updates the Path environment variable.

If you attempt to create a Salesforce driver ODBC data source from within Server Manager, you'll get error "The program can't start because essupp.dll is missing from your computer" if Server Manager was running prior to starting the Salesforce ODBC driver Setup program. The updated Path value isn't available to applications run from within Server Manager.

To solve this problem, exit and then start Server Manager again. You can now configure the ODBC data sources without getting this error.