jjones11:
Googling reveals this has been an issue since 2009, and apparently with every release of Arduino since! Tracking down and using the custom-built rxtxSerial.dll works fine (old fix - haven't yet tried Frederico's fix yet), but it's very disappointing that this has not been fixed by the powers-that-be years ago. Is this the normal mode of operation with Arduino?
Sadly yes. 
And it can't be said that it is because users fail to raise issues, or that devs are unwilling to commit changes and help improve Arduino, because there are hundreds of outstanding issues on github, and dozens of fixes and pull requests which never get incorporated.